Born in Salt Lake City, Utah, Young attended Greenwich High School in Greenwich, Connecticut, where he played quarterback on its Cardinals football team. He earned 1978 All-FCIAC West Division First Team honors in his junior year, his first year as a starter. In his senior year he rushed for 13 touchdowns and earned All-FCIAC West Division First Team honors, and was named to the CIAC All-State team. In the rush-first option offense run by Greenwich he completed only 41 percent of his throws for 1,220 yards, but ran the ball 267 times for 1,928 yards. On Thanksgiving Day in November 1979, Greenwich lost to Darien High School, known for its “Tidal Wave Defense”, 17–0. During his senior year, he was co-captain of the football, basketball and baseball teams. In basketball, he averaged 15 points a game. In baseball, he hit .384 and played center field when he wasn’t pitching. He was 5–1 and threw a 3–0 no-hitter against New Canaan High School.

In the three years following Super Bowl XXIX, the 49ers would be eliminated each year by Brett Favre and the Green Bay Packers, twice in San Francisco. In addition to the early playoff exits, Young suffered a series of injuries that forced him to miss several games from 1995 to 1997. Young entered the 1998 season at age 37 and some began to wonder if his skills would diminish because of his history of injuries and a general decline in his game due to age. However, he silenced all critics once again, putting up career numbers in passing yards (4,170) and passing touchdowns (36). The 49ers finally beat Favre and the Packers in an NFC wild card game that year, as Young threw the winning touchdown to wide receiver Terrell Owens with three seconds remaining to win the game 30–27. In reference to Dwight Clark’s legendary catch against the Dallas Cowboys in the 1981 NFC championship game, Owens’s grab was called “The Catch II”. A week later, however, Garrison Hearst broke his ankle on the 49ers’ first play from scrimmage. Without the threat of a running game, Young threw three interceptions (the last one a Hail Mary pass with under 30 seconds remaining in the game) and the 49ers were defeated by the Atlanta Falcons 20–18. Over that span of seasons from 1995 to 1998, Young led the NFL in passer rating twice (in 1996 and 1997), and led the NFL with 36 touchdown passes in 1998.

Young was heavily recruited by the University of North Carolina. Coach Dick Crum was enamored by Young’s running ability, and wanted him to run his option offense. Young instead chose BYU. Initially, he struggled at throwing the ball, and BYU’s coaching staff considered switching him to defensive back because of his athleticism. However, he worked hard to improve his passing skills and eventually succeeded record-setting Jim McMahon as BYU’s starting QB. Young’s senior season (1983) was spectacular. He passed for 3,902 yards and 33 touchdowns in the regular season, and his 71.3% completion percentage set an NCAA single-season record. He also added 544 yards rushing. With Young at quarterback, BYU set an NCAA record by averaging 584.2 yards of total offense per game, with 370.5 of those yards coming from Young’s passing and rushing. The Cougars finished the year with an impressive 11–1 record; Young was named First Team All-American by several news organizations and received the Davey O’Brien National Quarterback Award, which recognizes the nation’s best collegiate quarterback each year. He also finished second in voting for the Heisman Trophy, behind Nebraska running back Mike Rozier. Young capped his college career by scoring the game-winning touchdown on a pass from the halfback in BYU’s 21–17 victory over Missouri in the 1983 Holiday Bowl.

Young was selected by the Los Angeles Express in the first round (11th overall) of the 1984 USFL Draft. He signed a record ten-year, $40 million contract with the USFL’s Los Angeles Express in March 1984. He agreed to take his payment in the form of an annuity paid out over forty years to help the fledgling team.

It was taken for granted that Young would be the first pick in the 1984 NFL Draft, and that he would be selected by the then-moribund Cincinnati Bengals. Express general manager Don Klosterman told Young that if he signed with the Express, his head coach would be John Hadl, a former All-Pro quarterback who had shepherded John Elway through his first year in the NFL. Klosterman also told Young that Hall of Fame coach Sid Gilman, who had been hired as a consultant, would tutor him on how to be a pro quarterback. Young was convinced, and signed with the Express.

The league ceased operations in 1986 after losing most of its claims in an antitrust suit against the NFL, with its top talent absorbed by the NFL in a dispersal draft conducted in the aftermath.

The Buccaneers selected University of Miami quarterback Vinny Testaverde first overall in the 1987 NFL Draft because Young was deemed a bust. Young was traded to the San Francisco 49ers on April 24, 1987 to serve as a backup to Joe Montana. 49ers coach Bill Walsh was impressed by Young’s natural abilities, and believed his lackluster numbers were primarily due to the lack of talent around him in Tampa Bay.

Young played behind Montana for four years, but shone as a backup. Substituting for an injured Montana, early in the first quarter of a 1987 game against the Chicago Bears, he threw four touchdown passes in a 41–0 victory. In their 1987 divisional playoff game against the Minnesota Vikings, he replaced Montana in the second half after the team fell behind 27–10. The 49ers still lost the game, but Young had a good performance, completing 12 of 17 pass attempts for 158 yards and a touchdown, with one interception, while also leading San Francisco in rushing with 72 yards and a touchdown on six carries. On October 30, 1988, Young ran for a 49-yard, game-winning touchdown against the Vikings. He started the game out with a 73-yard touchdown pass to John Taylor, after Montana went down with an injury. The play earned the 49ers a 24–21 victory and a bit of revenge on the Vikings for their previous season’s playoff loss. The win turned out to be crucial, as without it the 49ers would have finished the season 9–7 and missed the playoffs, as two other teams in their division, the Los Angeles Rams and New Orleans Saints, had 10–6 records. Instead, the 49ers won their division, earned the #2 playoff seed, and went on to win the Super Bowl.

In 1989, he displayed potential to become the team’s starter in the future. While Montana won the NFL MVP award and led the team to victory in Super Bowl XXIV, Young still had a good season, completing 69% of his passes for 1,001 yards and eight touchdowns, with only three interceptions. On October 22, 1989, he posted a perfect passer rating of 158.3 when he completed 11 of 12 passes for 188 yards and three touchdown passes in a 37–20 victory over the New England Patriots.

He rushed for a career-high 102 yards on just eight carries against the New Orleans Saints on December 23, 1990, making him only the second 49ers quarterback to rush for at least 100 yards in a single game. The 49ers lost the game 13–10.

Following an injury to Montana’s elbow in the 1990 NFC Championship Game, which forced him to miss the entire 1991 season, Young got his chance to lead the 49ers. He got off to a rough start. Midway through the season, the 49ers found themselves struggling with a 4–4 record. In the ninth game of the season, after throwing a franchise-record 97-yard touchdown pass to Taylor, Young suffered a knee injury and was replaced by backup quarterback Steve Bono. After a loss in that game and the next, Bono led the 49ers to five consecutive victories, playing so well that coach George Seifert decided to keep him in the starting lineup after Young had recovered. It wasn’t until late in the 15th game of the season, after Bono went down with an injury of his own, that Young got to play again. Young then closed out the season by throwing for 338 yards and three touchdowns and also rushing for 63 yards and another touchdown in a 52–14 win over the Chicago Bears in a Monday Night Football game at Candlestick Park.

Young finished the season with an NFL best 101.8 passer rating. Despite missing five full games and most of a sixth, he still threw for 2,517 yards and 17 touchdowns with only 8 interceptions. But despite Young’s strong season, the season for the team was widely regarded as a disappointment. The 49ers had slipped from a 14–2 record in the previous season to a 10–6 record in 1991. While 10 wins is usually enough to make the playoffs, this time it was not, and San Francisco ended up not playing in the postseason for the first time since 1982. It was thought by many that Young’s days as the 49ers starter were numbered due to the impending return of Montana from the injury to his right elbow, and some observers said the 49ers should trade Young and keep Montana and Bono. However, the trade never happened.

In 1993, Young founded a charitable foundation known as the Forever Young Foundation, which serves children facing significant physical, emotional, and financial challenges by providing academic, athletic, and therapeutic opportunities otherwise unavailable to them.

In 1994, Young received a Juris Doctor (J.D.) from BYU’s J. Reuben Clark Law School.

Young has both performed dramatic roles and appeared as himself in a limited acting career. He appeared in one episode of Frasier and one episode of Lois & Clark: The New Adventures of Superman (cast as Lois’ former high school football quarterback boyfriend, Joe Maloy). He also made a guest appearance as himself in the Dharma & Greg episode “Are You Ready for Some Football?” encouraging Dharma, the team’s Number One Fan. In 1995, Young appeared as himself in the Season 6, Episode 12 episode of Beverly Hills, 90210. He also made cameo appearances in the LDS comedy The Singles Ward (2002) and in a season 5 episode of BYUtv’s Studio C (2014). Young also made a guest appearance as himself in season 8 of the NBC comedy series Wings in the episode “Just Call Me Angel”.

Young was originally offered a part in the 1998 movie There’s Something About Mary, but turned the role down. He was replaced by Brett Favre.

The 1999 season would turn out to be Steve Young’s last in the NFL. Young was plagued by concussions throughout his career. During a Week 3 Monday Night Football game against the Arizona Cardinals, Young was violently sacked by Cardinals’ cornerback Aeneas Williams due to a missed blocking assignment by 49ers’ running back Lawrence Phillips. Young was knocked out of the game with a concussion, and didn’t return again for the rest of the season due to symptoms of post-concussion syndrome. The concussion he suffered against the Cardinals was reportedly his second in a season that was only three weeks old, and the seventh (at least) of his career. Young was forced to retire at the end of the year; the team informed him that he would be released if he did not retire. Although Young was offered a job as the starting quarterback of the Denver Broncos (where his former offensive coordinator, Mike Shanahan, was the head coach), he retired because of his repeated concussions. In a 2013 Frontline interview, Young said that, partially based upon their own experiences, he and many retired players are increasingly concerned about repeated concussions and subconcussive hits. He is particularly concerned about certain positions that take frequent hits, such as running backs and linemen.

In 1999, he was ranked No. 63 on The Sporting News list of the 100 Greatest Football Players. Young was elected to the Pro Football Hall of Fame on February 5, 2005; he was the first left-handed quarterback to be so honored. He was enshrined August 7, 2005. His induction speech was given by his father, LeGrande “Grit” Young.

In 2000, Young spoke at the Republican National Convention.

Young finished his college career with 592 pass completions for 7,733 yards and 56 touchdowns, along with 1,048 yards and 18 touchdowns rushing. He was enshrined in the College Football Hall of Fame in 2001.

In 2007, Young co-founded Huntsman Gay Global Capital (HGGC), with billionaire industrialist Jon M. Huntsman and former Bain Capital executive Robert C. Gay. After being involved in business ventures with the private equity firm, he has continued to serve as a managing director.

The San Francisco 49ers had his No. 8 jersey retired during a halftime ceremony against the New England Patriots on October 5, 2008. He was the 11th player in team history to receive this honor. He is also the only 49er in team history to wear No. 8.

Young also serves as the national spokesman for an organization founded by former Save Darfur Coalition executive director and founder, David Rubenstein. He began his affiliation with the organization in 2009, when he became the honorary league commissioner for their charitable dodgeball tournaments held on college campuses nationwide.

In 2011, Young was one of several notable BYU athletes and coaches who appeared in the school’s “Real Cougar” advertising campaign, which featured the individuals telling an actual cougar about being a “real cougar”. In one of the ads, Young poked fun at himself: