Valderrama began his Major League Soccer career with the US side Tampa Bay Mutiny in the league's inaugural 1996 season. The team won the first ever Supporters' Shield, awarded for having the league's best regular season record, while Valderrama was the league's first Most Valuable Player, finishing the season with 4 goals and 17 assists. He remained with the club for the 1997 season, and also spent a spell on loan back at Deportivo Cali in Colombia, before moving to another MLS side, Miami Fusion, in 1998, where he also remained for two seasons. He returned to Tampa Bay in 2000, spending two more seasons with the club; while a member of the Mutiny, the team would sell Carlos Valderrama wigs at Tampa Stadium. In the 2000 MLS season, Valderrama recorded the only 20+ assist season in MLS history—ending the season with 26 — a single season assist record that remains intact to this day, and which MLS itself suggested was an "unbreakable" record in a 2012 article. In 2001, Valderrama joined the Colorado Rapids, and remained with the team until 2002, when he retired; his American soccer league career spanned a total of eight years, during which he made 175 appearances. In the MLS, Valderrama scored relatively few goals (16) for a midfielder, but is the league's fourth all-time leader in assists (114) after Brad Davis (123), Steve Ralston (135) – a former teammate, and Landon Donovan (145). In 2005, he was named to the MLS All-Time Best XI.