Richardson appeared in just four games during his first year at Florida in 2020, completing one of two passes for 27 yards with a touchdown and interception.[6][7] He was able to redshirt his first year of collegiate eligibility.[8] Richardson entered 2021 as the backup to Emory Jones.[9][10][11] Against the LSU Tigers, he replaced Jones and completed 10 of 19 passes for 167 yards with three touchdowns, two interceptions and a rushing touchdown.[12]
Richardson officially became the starting quarterback for the Gators in 2022. In the first game of the season, he helped lead a 29–26 upset over the seventh-ranked Utah Utes on September 3, 2022.[13] On September 24, in a 38–33 loss to the Tennessee Volunteers, Richardson passed for 453 yards, two touchdowns, and one interception to go along with 17 carries for 62 rushing yards and two rushing touchdowns.[14]
Overall, in 2022, Richardson played in 12 games and passed for 2,549 yards, 17 touchdowns and 9 interceptions, as well as rushing for 654 yards and 9 touchdowns in his first full season as a starting quarterback for a college team.[15] During his time at Florida, Richardson amassed a 6–6 record as the starting quarterback for the Gators.[16]
As a collegiate player, Richardson was stated to have displayed "dynamic talent" as a passer and runner during his college years. Richardson's physical gifts also helped propel him as a possible first-round NFL draft selection.[17] Following the end of the 2022 season, Richardson announced that he would enter the 2023 NFL draft.[18]
Richardson was drafted in the first round by the Indianapolis Colts with the fourth overall pick in the 2023 NFL draft.[20] Richardson's combine measurables ranked him as the most athletic quarterback prospect in league history according to the Relative Athletic Score (RAS) metric.[21][22] He joined Cam Newton and Daunte Culpepper as the only quarterbacks to have achieved a perfect RAS score.[23][24]
During his first training camp with the Colts, Richardson underwent nasal septum surgery to improve his breathing.[25][26] On August 15, 2023, Richardson was named by head coach Shane Steichen as the Colts' starting quarterback over Gardner Minshew and Sam Ehlinger.[27]
On September 10, 2023, Richardson made his NFL debut in Week 1 against the Jacksonville Jaguars. Richardson threw his first touchdown pass to Michael Pittman Jr., ran for a touchdown, and threw his first career interception to Tyson Campbell in the 31–21 loss.[28] In Week 2 against the Houston Texans, Richardson ran for two touchdowns before leaving the game with a concussion in the second quarter as a result of a hit taken as he scored his second touchdown.[29]
On September 22, 2023, Richardson was declared out in Week 3 due to a concussion he suffered in Week 2.[30] He returned the next week against the Los Angeles Rams and recorded two passing touchdowns and one rushing touchdown and erased a 23 point deficit in a 29–23 loss in overtime.[31] His rushing touchdown in this game marked the first time in NFL history that a rookie quarterback has scored a rushing touchdown in each of his first three starts.[32]
On October 9, 2023, Richardson was placed on the injured reserve due to a grade three AC joint sprain he suffered in Week 5 against the Tennessee Titans, which was initially announced for him to miss one to two months.[33] On October 18, 2023, the Colts announced that Richardson would miss the remainder of the season, and successfully underwent shoulder surgery to repair the sprain on October 24, 2023.[34][35]