During his MLB career, Damon played for the Kansas City Royals (1995–2000), Oakland Athletics (2001), Boston Red Sox (2002–2005), New York Yankees (2006–2009), Detroit Tigers (2010), Tampa Bay Rays (2011) and Cleveland Indians (2012).

[1][2] His mother, Yome, is a Thai immigrant to the United States and his father, Jimmy, is an American of Croatian and Irish descent.

He made his MLB debut on August 12, 1995, after playing the previous season with the minor league Wichita Wranglers.

[10][11] During Game 5 of the 2003 American League Division Series, Damon collided head-on with teammate Damian Jackson while both players were attempting to chase down a pop fly.

In arguably his best season in the Major Leagues, Damon batted .304 with 20 home runs and 94 RBIs and showed improved patience at the plate.

According to his autobiography, he was only the fourth leadoff batter in the history of Major League Baseball to drive in more than 90 runs in a season.

Damon batted a torrid 7-for-15 during that year's Division Series against the Angels[13] but struggled in the ALCS against the Yankees, going only 3-for-29 from the plate through the first six games.

Through his four-year career with the Red Sox (2002–2005), Damon appeared in 597 games (590 in center field and seven as a designated hitter)[15] and hit 56 home runs.

[8] The Red Sox stood firm on a three-year contract and chose not to negotiate against a five-year deal proposed by agent Scott Boras.

On June 7, 2008, Damon went 6-for-6 in the Yankees 12–11 win over the Kansas City Royals, including a walk-off ground-rule double, which had bounced over the wall.

The Yankees placed Damon on the 15-day disabled list for the first time in his MLB career on July 6, 2008, with a bruised AC joint in his left shoulder.

[24] For the 2009 season, he batted .282 and tied for the lead among AL left fielders in errors (with 5), while he was fourth in the league in runs scored (107).

Damon, after winning his second World Series, entered free agency after the 2009 season despite expressing his desire to return to the Yankees.

[27] The Yankees then signed outfielder Randy Winn to a one-year $2 million[28] deal which essentially closed the door on Damon's return to the Bronx.

The Rays also signed his former Boston Red Sox teammate Manny Ramirez in a package deal suggested by agent Scott Boras.

Manager Joe Maddon said he expected the 37-year-old Damon to often be replaced by Sam Fuld during the season late in games that the Rays are leading.

In Game 1 of the ALDS, Damon hit a two-run home run in the second inning off Texas Rangers starting pitcher C. J. Wilson to give his team an early 2–0 lead.

[41] Indians manager Manny Acta dropped Damon to seventh in the batting lineup after going 4–29 in the leadoff position, including 2 hits in his last 18 at-bats.

His first year of eligibility for the National Baseball Hall of Fame and Museum came in 2018 where he joined a notable group of first-time candidates, including Chipper Jones, Jim Thome and Omar Vizquel.

[48] In late 2013 and early 2014, Damon indicated a desire to keep playing, in part to have the opportunity to attain 3,000 hits (he needed 231 to reach that goal).

He told members of the media that he has stayed in good physical condition and hoped to receive invitations to spring training.

In a May 2014 interview while in Boston to celebrate the 10th anniversary of the Red Sox 2004 World Series championship, Damon indicated that he has no plans to officially announce his retirement, even though he acknowledged that he will likely not play in the major leagues again.

[53] On August 4, 2014, Damon gave an interview with the WEEI-FM radio show "Middays with MFB" and indicated that while he wants to still play, no teams have expressed an interest, and "those days are over".

[54] According to press accounts in December 2014, Damon hoped to play in 2015, and his agent told a reporter "If you ask Johnny, he'd love to come back.

In August 2019, Damon and his wife appeared as one set of primary charter guests during seasons 4 & 5 of the show Below Deck Mediterranean.

[70] He is active with the Wounded Warrior Project, which works to raise awareness and enlist the public's aid for the needs of severely injured service men and women.

[72] Damon spoke at a rally in Florida during Donald Trump's 2016 presidential campaign and chanted in support of a border wall between the United States and Mexico.

[74] On October 26, 2019, in Orlando, Florida, Damon was the Special Guest at the Orange County Republican Party's Trump Defender Gala and 2019 Annual Lincoln Day Dinner.

[77] Bodycam footage released by the Windermere Police Department showed Damon claiming that his arrest was part of being targeted because of his support of Trump.