Lofton struggled early in his professional baseball career in the Astros farm system. He hit .214 in 48 games as an outfielder for the Auburn Astros of the New York–Penn League, but recorded 26 stolen bases in 30 attempts. Lofton returned to Auburn in 1989 and hit .263 with 26 steals in 34 games. He then hit .329 with 14 steals in 22 games for the Asheville Tourists in the South Atlantic League. As his college basketball career came to an end, Lofton was able to concentrate on baseball and he improved rapidly, finishing second in the league in hitting at .331 while adding 62 steals for the Osceola Astros in the Florida State League. He also drew 61 walks and improved defensively (.974 fielding percentage) and played in 123 games with Osceola.

After spring training in 1991, he went directly to the Triple-A Tucson Toros of the Pacific Coast League. His 168 hits led the league. He hit .308 with 30 steals and 52 walks for Tucson with 19 doubles and a team-high 17 triples. The Toros won the PCL championship and Lofton made the league’s All-Star team. On September 14, 1991, the Astros promoted Lofton to the majors.

In his major league debut with the Houston Astros on September 14, 1991, he went 3-for-4 with a double and scored three runs against the Cincinnati Reds. He hit .203 in 20 games for the remainder of the Astros’ regular season. With Steve Finley already entrenched as Houston’s centerfielder, and aged 26 years, Lofton was traded during the off season to the Cleveland Indians for catcher Eddie Taubensee and right-handed pitcher Willie Blair. “I know they gave up on me and now I’m glad they did. One man’s trash is another man’s treasure”, Lofton said of the Astros trading him.

During his first season with Cleveland, in 1992, Lofton hit .285. His 66 stolen bases broke the all-time record for an AL rookie and was the most by an MLB rookie since Vince Coleman stole 110 in 1985. His season’s stolen-base count, which led the AL, also broke a franchise record (previously set by Miguel Diloné in 1980). Indians first base coach Dave Nelson helped Lofton refine his baserunning technique and helped him learn how to be successful with bunting. Lofton finished second (to the Milwaukee Brewers’ Pat Listach) in AL Rookie of the Year balloting. After one season with Cleveland, Lofton agreed to a four-year, $6.3 million contract. The following season, Lofton broke his own Cleveland single-season stolen bases record, recording 70 (which led the MLB). Lofton was selected to his first career All-Star Game during the 1994 season.

In 1995, Lofton was one of six Indians starters who batted .300 or higher (.310). He also had an MLB-best 13 triples. His 54 stolen bases led the AL for the third consecutive season. The Indians faced the Seattle Mariners in the 1995 ALCS. In the eighth inning of game six, Lofton had an infield bunt, stole second base, and scored from second on a passed ball between pitcher Randy Johnson and catcher Dan Wilson. The Indians won the game 4–0. It was described by The New York Times as “the run that demoralized the Mariners.” Fifteen years after Lofton’s crossing of home plate, the Plain Dealer recalled: “Of all the electrifying moments on the Kenny Lofton highlight reel, none captures the essence of the player any better than his 180-foot dash to glory on October 17, 1995.” As a result of winning the game, the Indians had won the ALCS and in so doing, Lofton and the Indians had brought the AL pennant to Cleveland for the first time since the 1954 season. “I’m glad for the city of Cleveland to be able to experience this, because they haven’t experienced this for a long time. The city of Cleveland has grown a lot, and it’s improving, and we tried to do this for the city”, Lofton said. The Indians lost the World Series to the Braves in six games despite finishing the regular season with a major league-best 100–44 record in the strike-shortened year. Lofton finished with a .200 batting average and six stolen bases in his first World Series appearance. In 2010, a few years into his retirement, Lofton stated he felt it was the toughest postseason loss of his 11 career playoff appearances, namely because he felt the umpires had favorable strike zones for Braves pitchers Tom Glavine and Greg Maddux.

The following season in 1996, the Indians again had the best record in baseball (99–62) and Lofton’s stolen base total (75) led the MLB for the second time in four years. He hit .317 and had a career-high 67 RBIs. The Indians lost in the 1996 ALDS to the Baltimore Orioles in four games. As an impending free agent, it was Lofton’s last season with Cleveland before being traded near the end of spring training 1997 to the Atlanta Braves of the National League (NL). On trading Lofton, Hart said, “We had to make this trade based on the fact that Lofton could be a free agent at the end of this season. We went through it with Albert Belle last year, and Albert left and we had nothing in return. We were not prepared to do that again.” Lofton, described as “an emotional and offensive catalyst” with the Indians, appeared in three consecutive All-Star games (1994–1996) and won four straight Gold Glove Awards (1993–1996) with the Indians. He led the AL in stolen bases for five straight seasons (1992–1996) and set the single-season Indians’ franchise stolen base record (75).

The Atlanta Braves’ Marquis Grissom and slugger David Justice were part of a Braves roster that, heading into the 1997 season, was the MLB’s highest-paid. Grissom ($4.8 million annual salary) and Justice ($6 million) were traded to the Indians in return for Lofton ($4.75 million) and Alan Embree ($206,000). “This is a trade of enormous magnitude for two very, very good franchises. We’re talking about franchise-type players”, Hart said. For Lofton, considered “the centerpiece of the Indians’ 1990s revival”, it was a return to the National League. “The trade will be in the back of my mind for a long time, but it’s baseball. It happens to nearly everybody. I’m [in Atlanta] to play every day. It’s all Braves from now on”, Lofton said. By April 19, the Braves were 13–3 and Lofton’s hitting (.453 batting average) had won favor with his new Braves teammates. “If he keeps hitting .400 he’ll fit in just fine”, said Chipper Jones. For the season, Lofton’s .333 batting average and 27 stolen bases were team highs (his stolen-base total was to that point a career low). He was caught stealing 20 times, an MLB high. Atlanta won the NL East division with an MLB-best 101–61 record. The Braves swept the Houston Astros in the 1997 National League Division Series (NLDS), three games to none. In the 1997 National League Championship Series (NLCS), the Braves lost to the Florida Marlins, four games to two (the Marlins later defeated the Cleveland Indians in the World Series). For the NLCS, Lofton batted .185 and was one of three Braves’ hitters who recorded seven strikeouts in the series. For Lofton, who was eligible for free agency at the end of the season, it was his only season with the Braves.

Lofton has his own television production company, FilmPool, Inc. In 1997, he appeared as a guest star on The Wayans Bros., and in 2004, he appeared as a guest star on George Lopez. Lofton co-wrote the song “What If” on Ruben Studdard’s 2006 album Soulful. In 2008, Lofton qualified for the American Century Celebrity Golf Classic. He played golf in the off season during his playing days. For the 2011 spring-training season, Lofton was hired by the Indians to coach baserunning and outfield work. He also served as a commentator on the Fox Sports West postgame show for the Los Angeles Dodgers. Lofton considers himself a perfectionist. “I love cleaning. I clean up, wash dishes, and make a good bed. I’m pretty neat. I’m a perfectionist. People come to my house and they’re like, ‘Man, do you actually live here?'”

Lofton, who was considered the “most sought-after free agent” following the 1997 season, returned to the AL and Cleveland Indians when he signed a three-year, $24 million contract. Happy to return to Cleveland, Lofton said, “It’s like I was a ghost for a year. But now I’m back.” Lofton’s .282 batting average was to that point the lowest of his MLB career, but his 87 walks were a career high. However, he had 64 RBIs, his second-highest RBI total, which had been 66 at that point in his career and doubled his stolen base count with 54 from the previous year’s total of 27. The Indians won the AL Central with an 89–73 record and their match-up against the Boston Red Sox, three games to one, in the 1998 ALDS. In the series against the Red Sox, Lofton’s .375 batting average led the Indians, as did his two stolen bases and six hits. The Indians lost the 1998 ALCS in six games to the New York Yankees, who had won 114 games in the regular season. Lofton tied for third-most number of hits and strikeouts and his 27 at-bats led the Indians. For the 1999 season, Lofton finished with a .301 batting average, the seventh time in eight MLB seasons hitting .300 or better. It was, however, the first season with Cleveland he did not record 50 or more stolen bases, finishing the season with 25. The AL Central-winning Indians (97–65) lost in the 1999 ALDS to the Boston Red Sox, three games to two. The Indians had led in the series two games to none before losing three games in a row and the series. Lofton and Roberto Alomar each had two stolen bases in the series, but Lofton recorded just two hits in 16 at-bats. In Game 5, Lofton dislocated his left shoulder and tore his rotator cuff while diving into first base.

On September 3, 2000, in a 12–11 win over the Baltimore Orioles, Lofton tied an MLB record previously held by Red Rolfe when he scored in 18 consecutive games. He tied an Indians’ franchise single-game record with five stolen bases and won the game with a 13th-inning walk-off home run. He finished the 2000 season batting .278, recording 30 stolen bases and 107 runs (the sixth time crossing home plate 100 times or more in nine seasons). The Indians finished the regular season 90–72 and one game out of the wild card. After missing the postseason in 2000, the Indians returned in 2001 after winning the AL Central with a 91–71 regular-season record. Before winning the division, however, Lofton scored the game-winning run during an August 5 game against the Seattle Mariners; the Indians were down by 12 runs, and became just the third team in MLB history to overcome such a deficit, winning 15–14 in 11 innings. Indians catcher Eddie Taubensee, who was involved in the trade which sent Lofton from Houston to Cleveland at the beginning of his MLB career, caught Lofton after he slid into home plate and jumped with excitement after discovering he had just scored the game-winning run. “I caught him and wasn’t going to let him go”, Taubensee said. Cleveland won that game against Seattle, but lost their match-up with the 116-win Mariners in the 2001 ALDS. He hit 66 RBIs on the regular season (second-most in his career), but failed to record 20 stolen bases for the first time in his major-league career and batted a career-low .261. Lofton had been treated for a rib cage problem that had affected his play before the All-Star break. His second stint with Cleveland lasted through 2001, in which his salary was for $8 million in his final contract year with the club. He became a free agent at the conclusion of the season.

A free agent in 2002, Lofton signed a one-year, $1.025 million contract with the Chicago White Sox. “I looked at the different opportunities that I had and this was a team that won 83 games last year while they were banged up. Cleveland lost four good players from last year’s team, and that’s going to be hard to replace. This was an easy decision”, Lofton said on signing with the White Sox. White Sox general manager Kenny Williams had stated when Lofton was healthy, like he was during the second half of the 2001 season, Chicago had obtained one of the best leadoff hitters in the game. When the White Sox were paired against the Indians in April during a three-game series at Chicago, the Indians were on a 10-game winning streak and at 11–1, had the best record in the majors. The White Sox ended the streak and for the series, Lofton was 6-for-14 with six runs scored. “You can’t say enough about him, his effort, his intensity. He’s been simply amazing”, said White Sox manager Jerry Manuel. Lofton appeared in 93 games with the White Sox and hit .259 with 42 RBIs and 22 stolen bases. On July 28, he was traded to the San Francisco Giants of the NL for minor leaguers Ryan Meaux and Félix Díaz.

In the Giants’ match-up with the St. Louis Cardinals in the 2002 NLCS, Lofton delivered a key hit to help the Giants win their first pennant since 1989. In the ninth inning, Cardinals manager Tony La Russa summoned left-handed reliever Steve Kline to face Lofton, who had already notched two singles in the game. Giants manager Dusty Baker considered bringing a right-handed hitter to pinch-hit for Lofton, but decided against doing so on the advice of his 3-year-old son. Lofton hit a first-pitch single to the outfield, scoring David Bell from second base and creating a 2–1 Giants victory. After the game, Baker remarked, “I just knew Kenny was focused and I know you can’t keep Kenny down for too long. That’s why we got Kenny over here. He’s a big-game player and he’s been great in the playoffs.” The Giants held a five-run lead in the seventh inning of game six of the World Series against the Anaheim Angels, but eight outs away from winning the World Series, the Angels rallied to win 6–5. The Angels took game seven the following night, with Lofton flying out to Darin Erstad in center to end that game and the World Series, and for the second time in his career, Lofton had lost a World Series.

From 2002 to 2007, Lofton played for eight teams and made it to the postseason with four of them. Joe Torre said, after Lofton had been to the playoffs in 11 of the past 13 seasons and played for 11 clubs in his career, “He bounced around a lot of clubs for a reason: They felt he could help them. He did a hell of a job.” As Rollie Fingers wrote, “On one hand, Lofton could be seen as a catalyst who magically sparked his teams into playoff contention, but others could say that it was simply a case of top playoff contenders repeatedly seeing him as the final piece of their puzzle.”

The Pittsburgh Pirates signed Lofton to a one-year, $1.025 million contract to begin the 2003 season. With the Pirates, he hit .277 and stole 18 bases in 84 games before being traded to the Chicago Cubs, where he was reunited with manager Dusty Baker. When Lofton joined the Cubs in July, he was joining a team that just one season before had lost 95 games. “With Kenny Lofton, we got a quality lead-off man”, said Cubs general manager Jim Hendry. In 56 regular-season appearances with the Cubs, Lofton stole 12 bases and hit .327. Lofton and the Cubs won the NL Central division (88–74). The Cubs’ postseason berth was just the sixth time since the divisional series format was introduced (1969) that a team made the postseason after having lost 95 games or more the previous season. Chicago beat the Atlanta Braves three games to two in the 2003 NLDS. Lofton hit .286 in the series and led the Cubs with three stolen bases and 21 at-bats. The Cubs, who were up in the series three games to one, held a three-run lead in the eighth inning of game six of the 2003 NLCS. The Florida Marlins scored eight unanswered runs, all in the eighth inning, to win game six and won game seven the following night to eliminate the Cubs. Lofton’s .323 against the Marlins led the Cubs’ starting line-up, as did his 31 at-bats, and he had the team’s only stolen base of the seven-game series.

Lofton was again on the move when on December 23, 2003, the New York Yankees signed him to a two-year, $6.2 million contract. During a Yankees’ road game at Cleveland, Lofton recorded his 2,000th career hit. After Lofton’s single, Indians fans began an ovation in honor of Lofton. “I didn’t know what to expect. I figured I’d get a few claps. It was touching. I tipped my hat, but they just kept going. If there was a storybook way for me to get it, to get it in Cleveland, it was something to remember.” New York finished the regular season with an AL-best record, 101–61. To begin the postseason, the Yankees defeated the Minnesota Twins, three games to one, in the 2004 ALDS. In the 2004 ALCS against the Boston Red Sox, the Yankees had built a 2–0 series lead when Lofton stated, “My ultimate goal is for me to try to win a championship. I’m at a point in my career – I’ve been here for 13 years, and gotten close. This is an opportunity for me to have a chance at it again.” Then Yankees went up in the series three games to none before becoming the first team in MLB history to lose a series after holding a 3–0 series lead.

Lofton, who appeared in 83 games with the Yankees, felt manager Joe Torre did not use his skills appropriately. Lofton finished the regular season with a .275 batting average and a career-low seven stolen bases. With the Yankees looking to reshape their roster and the Philadelphia Phillies looking for a player with postseason experience, Lofton was dealt on December 3, 2004, which as part of the deal also had the Yankees sending $1.525 million to Philadelphia and the Phillies giving up reliever Felix Rodríguez. After the trade, Lofton stated, “It’s been very tough. I’m the kind of guy who likes to be settled down. It’s been very tough the last three or four years. Everyone in New York understood I wanted to play. I just wanted an opportunity to perform and be a part of the team. I didn’t feel as much of a part of the team.”

On December 12, 2006, the Texas Rangers signed Lofton to a one-year contract. By signing with the Rangers, Lofton tied Todd Zeile for most teams played for by a position player. In 84 games with the Rangers, he hit .303 with 16 doubles.

On July 27, 2007, Lofton was traded by the Rangers to the Indians in exchange for minor-league catcher Max Ramírez. “That’s my biggest thing right now. I’m trying to get a World Series ring”, Lofton said on joining the Indians for the third time in his career. The Jacobs Field crowd greeted Lofton with a standing ovation during his first at-bat for this tour of duty with the Indians. Lofton noted, “I missed being in Cleveland… I enjoy Cleveland. It’s the city that got me going.” In game one of the 2007 ALDS against the Yankees, he went 3-for-4 with four RBIs and one stolen base, which tied him with Rickey Henderson for the MLB’s all-time postseason stolen bases record (33). In game two, he went 2-for-3 with two walks and scored the winning run in the 11th inning. Then, in Game Three of the 2007 ALCS, the 40-year-old Lofton hit a two-run home run against the Boston Red Sox’ Daisuke Matsuzaka, becoming the seventh-oldest player to hit a postseason home run. Lofton earned his 34th career postseason stolen base in game four of the 2007 ALCS, setting a new MLB record for playoff steals. The Indians, who at one point had a 3–1 game lead over the Red Sox, eventually lost the series. In game seven, Lofton was called out while attempting to steal second base, but the replay showed that he was safe. He was also held up at third base while attempting to tie the game, in a call that was criticized by Cleveland fans for years. Lofton became a free agent at the end of the season, but did not sign a contract with an MLB team. He expressed interest in playing before the 2009 season.

On January 27, 2010, Lofton was announced as being selected as a member of the Cleveland Indians Hall of Fame. He was inducted on August 7.

Lofton was eligible for the National Baseball Hall of Fame in 2013 and some have written his career numbers “will likely put him in the conversation of being Hall of Fame worthy.” He did not receive the necessary number of votes to remain on the ballot for 2014 and beyond. In 2015, Pedro Martínez, one of the most dominant pitchers of Lofton’s era, named Lofton as among the most difficult hitters to pitch against in his career.