On August 23, in a 3–1 win over the Mets, Bumgarner won his 109th career game, surpassing Lincecum for sole possession of third place in the San Francisco Era and the most wins by a pitcher under Bruce Bochy’s managerial career. He registered a pinch-hit walk-off RBI single off of Rowan Wick on September 25, knocking in Gorkys Hernández from third base in the bottom of the twelfth inning to give the Giants a 5–4 win over the Padres. It was Bumgarner’s first career walk-off hit and the first by a Giants pitcher in twenty-eight years. Don Robinson was the last Giants pitcher to do so in 1990. In 21 starts, Bumgarner had a 6–7 record, a 3.26 ERA, and 109 strikeouts in 129 ⁄3 innings pitched. On October 29, the Giants exercised Bumgarner’s 2019 contract option worth $12 million.

The San Francisco Giants selected Bumgarner in the first round, with the tenth overall selection, of the 2007 MLB draft. Going into the draft, Baseball America had ranked him as the 14th-best prospect overall. He was the first high school pitcher to be selected as the Giants’ first pick since Matt Cain in 2002, and the first left-handed pitcher selected in the first round by the organization since Noah Lowry in 2001.

In a 3–1 win over the Astros on August 11, Bumgarner pitched a complete game. He struck out 12 Houston batters, including a career-high seven straight batters to tie a San Francisco record with Juan Marichal and Jonathan Sánchez. Meanwhile, he avoided walking any Astros. On August 16, he tied his career-high by recording 14 strikeouts, including three against Bryce Harper, who would go on to win the NL MVP award that year. Bumgarner also hit his tenth career home run and pitched a complete game shutout as the Giants beat the Nationals 5–0. He became the first Giants left-handed pitcher to record multiple fourteen-strikeout games in a single season and career, and joined Marichal as the only Giants pitchers in the San Francisco era to strike out ten or more batters, hit a home run, and record a shutout in the same game. For his exploits the week of August 9 through August 15, Bumgarner won the National League Player of the Week Award. On August 18 at Busch Stadium, in a 2–0 win over the St. Louis Cardinals, Bumgarner logged his first career pinch-hit, a two-out single to left field in the top of the seventh inning off of Lance Lynn. He became the first Giants pitcher to record a hit in a pitch-hitting appearance since Kirk Rueter in 2004. On August 21 at PNC Park, in a 6–4 win over the Pittsburgh Pirates, Bumgarner hit his fifth home run, the most since Carlos Zambrano in 2006. On August 28 at AT&T Park, in a 9–1 win over the Chicago Cubs, Bumgarner struck out twelve batters through six innings, the third out of four games in which he finished with ten or more strikeouts.

Bumgarner attended South Caldwell High School in Hudson, North Carolina, where he was known as “Maddie” and played on both the school’s baseball team and the Post 29’s American Legion Baseball team. In his junior season, he had a 12–2 win–loss record, an 0.99 earned run average (ERA), and 120 strikeouts in 84 innings pitched as he led his team to a runner-up in the 2006 4A State Championship. The next season, he went 11–2 with a 1.05 ERA and 143 strikeouts in 86 innings while his team won the state championship. He hit .424 with 11 home runs and 38 runs batted in (RBIs). He was named most valuable player (MVP) of the playoffs and the Gatorade North Carolina Player of the Year, garnering the nickname “The Carolina Peach.” Bumgarner attracted so much attention from scouts and agents in high school that his father built a wall around the bullpen at his high school field to keep them from distracting him as he warmed up. He committed to attend the University of North Carolina at Chapel Hill on a college baseball scholarship.

Bumgarner pitched for the Augusta Greenjackets, the Giants’ Low-A South Atlantic League affiliate, in 2008. The Giants had him alter the angle of his head during delivery, but after Bumgarner struggled over his first three starts in Augusta, he reverted to the way he had thrown in high school. With Augusta, he worked on his changeup, slider, and ability to throw effectively on the inside part of the plate, a critical trait for a pitcher with his side-armed delivery. He won the South Atlantic League pitchers’ Triple Crown, tying for the league lead in wins (15, tied with Levi Maxwell), leading the league in ERA (1.46), and leading the league in strikeouts (164). He began the 2009 season with the Giants’ High-A affiliate, the San Jose Giants of the California League. After five starts, in which he went 3–1 with a 1.48 ERA and 23 strikeouts, he was called up to the Giants AA affiliate, the Connecticut Defenders of the Eastern League. On July 22, he hit a grand slam against Eric Niesen and picked up the victory in a 9–3 triumph over the Binghamton Mets. In 20 games (19 starts) with them, he went 9–1 with a 1.93 ERA and 69 strikeouts.

In 2008, Baseball America ranked him the third-best prospect in the Giants organization. Before the start of the 2009 season, the magazine ranked Bumgarner as the ninth-best prospect in baseball. Entering 2010, Bumgarner attended the Giants’ spring training before the season, competing for the position of fifth starter. He dropped to the fourteenth-best prospect in baseball on the magazine’s list, as some writers were concerned about a drop in Bumgarner’s velocity. Out of shape entering the new season, he struggled and was sent down to the AAA Fresno Grizzlies, partly due to his loss of velocity. In 14 starts with Fresno, he went 7–1 with a 3.16 ERA and 59 strikeouts.

The Giants promoted Bumgarner to the major leagues for his debut in a start against the San Diego Padres on September 8, 2009. He started in place of ace Tim Lincecum, who was scratched with back spasms. At the age of twenty and thirty-eight days, he became the second-youngest pitcher ever to start a game for the Giants, older only than Mike McCormick, who started two games for the Giants—as a nineteen-year-old—in 1956, when the team was still in New York. In the bottom of the third inning with no outs, Bumgarner struck out Padres’ pitcher Kevin Correia for his first career strikeout. Bumgarner made four appearances with the Giants in 2009, posting an ERA of 1.80, striking out ten batters, and pitching ten innings.

On June 26, 2010, Bumgarner was called up again to join the club, facing the Boston Red Sox the next day, where he registered his first career major league hit. He replaced Joe Martinez, who had made one start in place of an injured Todd Wellemeyer, in the starting rotation. The next day, Bumgarner made his first career major league pinch-hitting appearance. On July 6, Bumgarner earned his first career major league victory by going eight innings without yielding a run. In the game, he also registered his first career major league run batted in (RBI). Bumgarner pitched well enough that when Wellemeyer returned from the disabled list in August, Giants’ manager Bruce Bochy chose to use him in the bullpen and leave Bumgarner in the rotation.

In five September starts during the Giants’ successful run to the National League West Division championship, Bumgarner posted an ERA of 1.13. At the end of September, Bumgarner earned his first win at home, making him 7–6 on the season. After the season, he was named a starting pitcher on Baseball America’s 2010 All-Rookie Team.

Bumgarner’s parents are Kevin and Debbie. Kevin works nights at a food distribution company, while Debbie is an accountant for PepsiCo. Bumgarner has a stepsister and two older half-brothers. Bumgarner had a half-sister, Dena, who died in 2010 after accidentally overdosing on pain medication following hospitalization from cancer. Bumgarner has been a Baptist since his childhood. Andrew Baggarly, a reporter who covers the Giants, wrote of Bumgarner, “While I wouldn’t describe him as outgoing, he struck me as being smart, well spoken and polite. He is deeply Christian and seems to be very grounded.”

Bumgarner married his high school sweetheart, Ali Saunders, on February 14, 2010, in a private ceremony in which he wore “a white open-collar shirt and blue jeans while carrying a pocketknife.” During the offseason, they live on a farm in North Carolina that is about thirty minutes from where he grew up in the old furniture manufacturing area of the state, and during the season in a condo in San Francisco. Bumgarner plays catch with his wife Ali, who grew up playing softball.

Bumgarner was 0–5 with a 4.58 ERA in his first seven starts of the 2011 season. Despite pitching at least six innings and giving up more than one earned run only once in his five starts from April 27 through May 19, 2011, it was not until the 19th that he got his first win, collecting an ERA of 3.71 for the season at that point. On May 19, 2011, at Dodger Stadium, in a 3–1 win over the Los Angeles Dodgers, Bumgarner pitched 8 ⁄3 before allowing a run in the ninth inning, nearly throwing his first career complete game shutout and outdueling 2009 All-Star Dodger pitcher Chad Billingsley. He threw a career-high 89 strikes on the outing. By June 9, Bumgarner had a 1.93 ERA over his last nine starts, yet had two wins and five losses to show for it. In seven of his eight losses at that point, the Giants either only scored once or scored no times at all.

On April 17, 2012, Bumgarner and the Giants agreed to a six-year contract extension worth $35.56 million through the 2017 season. The contract includes additional $12 million options for 2018 and 2019. Bumgarner began the season by going 5–1 with a 2.31 ERA. On June 12 at AT&T Park (the Giants’ home stadium), in a 6–3 win over the Houston Astros, Bumgarner hit his first major league home run and also struck out twelve batters. On June 28 at AT&T Park, in a 5–0 win over the Cincinnati Reds, Bumgarner pitched both his first career regular-season complete game and regular-season complete game shutout. With this victory, it marked the first time in franchise history with four straight shutouts and established a new San Francisco record of thirty-six consecutive scoreless innings. He finished the year with a 16–7 record while posting a 3.37 ERA and striking out 191 batters in 208 ⁄3 innings.

In 2013, the North Carolina High School Athletic Association included him on its “100 To Remember” male athletes list, which included Michael Jordan, Carl Eller, and Jim Beatty.

Bumgarner set career bests for ERA (2.77), walks plus hits per inning pitched (WHIP) (1.03) and strikeouts (199) in 31 starts, finishing with a 13–9 record. He threw over two hundred innings for the third consecutive season (201 ⁄3) and improved at holding runners on base, conceding eight stolen bases in 2013 as opposed to 27 in 2012. Bumgarner finished in ninth place in voting for the NL Cy Young Award.

For the first time in his career in 2014, Bumgarner started for the Giants on Opening Day. On April 11, Bumgarner hit his first career grand slam and registered a career-high five RBIs. Bumgarner was named NL Pitcher of the Month for May after going 5–0 in six starts, with 48 strikeouts and a 2.08 ERA.

In the 2014 World Series, the Giants faced the Kansas City Royals. Bumgarner started Game 1, allowing one run in seven innings, ending his consecutive scoreless innings on the road streak at 32 ⁄3 innings. He earned the win in the Giants’ 7–1 triumph. In Game 5, Bumgarner pitched his second career postseason complete-game shutout, another four-hit shutout, becoming the second pitcher in franchise history with two shutouts in a single postseason after Mathewson’s three shutouts in the 1905 World Series and the first San Francisco Giants pitcher to throw a complete-game shutout in a World Series game since Jack Sanford in the 1962 World Series. He set all-time MLB records for lowest World Series ERA (0.29) among pitchers of at least twenty-five innings pitched and three starts, and was the first pitcher in World Series history to pitch a shutout with at least eight strikeouts and no walks. On October 29, in Game 7 of the World Series against the Kansas City Royals, on two days rest, Bumgarner pitched five scoreless innings in relief, preserving a one run lead and earning the save as the Giants won their third title in five seasons.

Bumgarner again started for the Giants on Opening Day in 2015 (April 6), holding the Arizona Diamondbacks to one run and earning the win in an eventual 5–4 victory. He pitched 7 ⁄3 scoreless innings and struck out six batters on May 4, 2015, in a 2–0 win over the Padres. He took a no-hitter into the seventh inning, but Justin Upton spoiled it with a leadoff single. On May 21, Bumgarner became the first pitcher to hit a home run off of Kershaw, who became the second Cy Young Award winner to surrender a home run to Bumgarner, joining Zack Greinke. Later in the year, on June 23, Bumgarner again pitched 7 ⁄3 innings against the Padres. This time, he struck out a career-high fourteen batters, tying Atlee Hammaker’s franchise record for most strikeouts in a game by a left-handed pitcher. Five days later, in a 6–3 win over the Colorado Rockies, Bumgarner had two hits, one a solo home run, scored twice, and struck out Brandon Barnes for his 1,000th career strikeout. He became the third left-handed pitcher in the San Francisco era and the third-youngest in franchise history to reach the milestone. Only Amos Rusie (21) and Mathewson (25) were younger. For the third year in a row, Bumgarner was part of the NL All-Star team. This time, he got to pitch in the game, throwing a scoreless fourth inning with batterymate Posey catching him.

For the third year in a row, Bumgarner made the Opening Day start for the Giants in 2016 (April 4), lasting only five innings and allowing three runs but earning the win in a 12–3 triumph over the Milwaukee Brewers. In his next start (April 9), Bumgarner hit another home run off of Kershaw, though the Giants lost the game to the Dodgers by a score of 3–2. From April 20 to June 20, Bumgarner allowed two earned runs or fewer in 12 consecutive starts, tying Fred Anderson for the third-longest streak in Giants history since 1913. In recognition of his hitting ability, the Giants used him instead of a designated hitter on June 30 at the Oakland Alameda Coliseum. That was the first time a pitcher batted for himself at the beginning of a game at an AL stadium since 1976, and only the fifth time since the creation of the designated hitter rule in 1973. He went 1-for-4 with a double.

Bumgarner faced defending NL Cy Young Award winner Jake Arrieta on September 3. He struck out ten batters and walked nobody in a 3–2 win over the eventual World Series Champion Chicago Cubs, notching his thirtieth career double-digit strikeout game, surpassing Mathewson’s twenty-nine for second place in Giants franchise history behind only Lincecum’s thirty-six. Against the Dodgers on September 20, Bumgarner had another 10-strikeout game with no walks. With his 240th strikeout of the season, he broke Cy Seymour’s Giants’ record for strikeouts in a single season by a left-handed pitcher, which had stood since 1898. Bumgarner picked up his one hundredth career win against the Dodgers on September 30, becoming the twenty-fourth Giant to reach the mark. He became the third Giant of the year to win his one hundredth career game on the 2016 season, joining Cueto and Cain. In 34 starts (which led the league), Bumgarner had a 15–9 record, a 2.74 ERA, and 251 strikeouts in 226 ⁄3 innings. His 251 strikeouts ranked third in the league, behind Scherzer’s 284 and José Fernández’s 253); his 2.74 ERA was fourth, behind Kyle Hendricks’s 2.13, Jon Lester’s 2.44, and Noah Syndergaard’s 2.60. Bumgarner was fourth place in voting for the NL Cy Young Award (behind Max Scherzer, Lester, and Hendricks); he finished sixteenth in NL MVP voting and was second to Scherzer among pitchers in voting.

In his fourth consecutive Opening Day start on April 2, 2017, Bumgarner gave up three runs in seven innings and hit two home runs, including one against Greinke. He became the fourth Giants pitcher and the first in the San Francisco Era to hit a home run on Opening Day, joining Mickey Welch (May 1, 1884), Larry Benton (April 18, 1929), and Johnny Antonelli (April 17, 1956). The second home run made him the Giants’ record-holder in home runs by a pitcher, pushing him past Hal Schumacher. Bumgarner also joined Carlos González and Joey Votto as the third player to hit multiple home runs off of both Kershaw and Greinke. However, the Giants lost 6–5 to the Diamondbacks. . His season was abruptly interrupted by his first stint on the disabled list beginning April 21 after he suffered injuries to his throwing shoulder and ribs in a dirt bike accident. He was out for nearly three months with the injury, returning on July 20 against the Padres. Bumgarner received a no-decision in a 5–3 defeat. His first win of the year did not come until five days later, against the Pirates. With a 3–5 record on August 15, Bumgarner lost his next four decisions before winning his last game of the year to finish with a 4–9 record. In 17 starts, Bumgarner had a 3.32 ERA and 101 strikeouts in 111 innings pitched. After the season, the Giants exercised Bumgarner’s 2018 contract option worth $12 million.

As in 2017, Bumgarner missed much of the first half with an injury. This time, it was a broken finger suffered in spring training. The injury required surgery and kept him from pitching for the Giants until June 5. He picked up his first win of the year in his fourth start, a 3–0 win over the Padres on June 21. Six days later, in a 1–0 walk-off win over the Rockies, Bumgarner struck out leadoff hitter DJ LeMahieu for his fifteen hundredth career strikeout, becoming the fourth-fastest left-handed pitcher since 1920 to reach the milestone. It was his 239th career game; Randy Johnson (206), Kershaw (218), and David Price (236) were the only ones since 1920 to reach 1,500 strikeouts quicker. From June 16 through July 2, he threw 22 straight scoreless innings. Bumgarner picked up his 106th career win in a 13–8 win over the Cardinals on July 8, surpassing Rueter for the most wins by a left-handed pitcher in the San Francisco Era.

With his fifth career Opening Day start on March 28, 2019, Bumgarner joined Marichal as the only pitchers to make at least five Opening Day starts for the San Francisco era Giants. He joined Carl Hubbell as the only left-handed pitchers in franchise history to reach 1,600 strikeouts, but the Giants lost 2–0 to the Padres. On June 15, he passed Hubbell’s strikeout total in a game against the Brewers. Though he gave up five runs (three earned), the Giants won 8–7, with Bumgarner receiving a no-decision. He held the Rockies to two runs in six innings on June 25 and drove in the Giants’ third run with an RBI single in a 4–2 victory. In an 8–4 win over the Cardinals on July 6, Bumgarner was removed after two innings due to being hit by a batted ball in the first inning. However, he had two strikeouts in the game, passing Lincecum’s 1,704 to move into fourth place all-time by a Giant.

On December 17, 2019, Bumgarner signed a five-year contract with the Arizona Diamondbacks, worth $85 million.

On July 24, 2020, Bumgarner made his Diamondbacks debut as a Opening Day starting pitcher. He was placed on the disabled list on August 10, 2020. In his last outing, he touched 85-87 MPH against the Padres. In his first 4 starts for Arizona, he was 0-3 with 7 home runs allowed.

On February 23, 2020, Bumgarner revealed in an interview for The Athletic that he has competed in rodeo events as a team roper under the alias Mason Saunders, combining a shortened version of his first name with his wife’s maiden name. He said that he had been roping since his mid-teens—long enough that “it’s part of who you are”—and he has been discreetly competing in rodeos for some time, including during his MLB career. Bumgarner, who added that he was frequently recognized at rodeo events, won over $26,000 in a competition in Wickenburg, Arizona about two weeks before he signed his Diamondbacks contract, and said that he may pursue roping more seriously after the end of his MLB career.