Thomas James Pham was born on March 8, 1988, in Las Vegas, Nevada, to Tawana, aged 17 and Anhtuan, aged 19. He is the elder of fraternal twins, with sister Brittany, whose birth occurred two minutes after his. At the time of their birth, Anhtuan was incarcerated, as he would be for most of their lives. Anhtuan was born in Vietnam to a Vietnamese mother and an African American father and moved to the United States with his mother, brother and sister. Anhtuan excelled at American football but became entangled in drugs and street crime. He was shot and injured by an off-duty police officer in Washington, D.C., in 2016 after he was caught stealing frozen crab legs from a supermarket.

Pham suffers from keratoconus, a rare eye disorder which causes degenerative vision problems. It was not until Pham began wearing contact lenses in 2009 that he became able to track pitches to the best of his ability.

The start to Tommy Pham’s professional baseball career has taken a number of detours due to injury. He suffered a broken wrist in 2010. In a 2011 game while attempting to deny a home run ball, he tore a ligament. He played 40 games and batted .294. In early 2012, while diving for a baseball, Pham noticed a pop in his shoulder. The opinion of team doctors was that it was not serious. He continued play but it worsened, and later examination showed a torn labrum, costing him nearly all of the season. After promotion to AAA Memphis Redbirds of the Pacific Coast League (PCL) in 2013, he tore his other labrum. He returned to Springfield after rehabilitation and batted .301 in 45 games. Pham played most of the 2014 season for Memphis, appearing in 104 games, and he batted .324 with a .395 on-base percentage (OBP), .491 slugging percentage (SLG), 63 runs scored, 16 doubles, six triples, 10 home runs (HR) and 44 runs batted in (RBI).

He was called up to the major leagues with the Cardinals for the first time on September 7, 2014.

He opened the next season with Memphis but missed the first two months with a quadriceps injury. On June 9, Pham hit two home runs and a career-high five RBI against the Iowa Cubs. In his first 24 games after returning from the disabled list, he batted .338 with a .402 OBP, .625 SLG, five home runs and 21 RBI. The Cardinals recalled him to the major league club on July 3, 2015, and he was influential in a 2–1 victory over the San Diego Padres the next day. He doubled for his first major league hit, then, later in the game, pilfered his first stolen base and scored the winning run, his first major league run. On July 5, Pham hit his first major league home run the day after collecting his first major league hit. He hit another double that game, and drove in all three of the Cardinals’ runs – also his first three major league RBI – as the Cardinals again defeated the Padres, 3–1.

The Cardinals selected Pham for the Opening Day roster in 2016. However, he injured his oblique in his first at bat on Opening Day, in the first inning versus the Pittsburgh Pirates. Thus, he was the first player following the start of the regular season to be placed on the DL. The club reactivated him from the DL on May 17 and optioned him back to Memphis. His home run on August 2 against the Cincinnati Reds was the Cardinals’ 11th pinch hit home run of the season, establishing a new club record. For the season, he had the highest strikeout percentage against left-handed pitchers (41.7%).

On May 7, 2017, Pham homered twice versus the Atlanta Braves at SunTrust Park among producing a season-high four hits. His second home run provided the deciding runs in a 6−4, 14-inning victory. Pham continued to produce both offensively and defensively, and he eventually became the starting right fielder. Through August 12, he was batting .309/401/.498, while leading the club in steals and outfield assists. He finished the season batting .306/.411/.520 with 23 home runs, 73 RBIs, 22 doubles, and 25 stolen bases in 128 games. He became the first Cardinals batter since 1900 to record at least a .300 average, 20 home runs, 20 doubles, and 20 stolen bases in the same season. He also was 3rd in the league in power-speed number (24.0). In his age-29 season, Pham placed tenth in the majors in Fangraphs’ Wins Above Replacement (WAR). He ranked 11th in the National League Most Valuable Player Award (NL MVP) voting, the only Cardinals player to receive votes.

On July 31, 2018, the Cardinals traded Pham to the Tampa Bay Rays along with $500,000 of international pool space for Justin Williams, Génesis Cabrera, and Roel Ramírez. At the time of the trade, Pham was batting .248 with 14 home runs and 41 RBIs. Following the trade, he stated, “I’m just disappointed. I wanted to give more. I wanted to give more, from a playing perspective. I got involved in the community. I really enjoyed being able to do that. But I wish I had given more. I had an opportunity here. They gave me a chance,” and “It hurts, specifically for me because I’ve been underperforming from my expectations. I feel like if I had just done my job better, we wouldn’t be so far down in the standings.”

On April 5, 2019, Pham reached base for the 40th straight game, the longest in Rays history. On April 6 Pham hit his first ever grand slam. In 2019 he batted .273/.369/.450, and led the major leagues in infield hits (25). On defense, he had the best fielding percentage of all major left fielders (1.000).

On December 6, 2019, Pham and Jake Cronenworth were traded to the San Diego Padres in exchange for Hunter Renfroe, Xavier Edwards, and a player to be named later. The trade was held in limbo due to concerns from an elbow injury that Pham was playing through at the end of the 2019 season even though Pham passed a series of physicals. The trade was finalized 5 days after it was completed.

On July 3, 2020, it was announced that Pham had tested positive for COVID-19.

Pham received surgery at UC San Diego Health following a stabbing, which took place on October 11, 2020, during a fight in San Diego outside a local strip club called Pacers Showgirls.