In high school, Washington earned 2018 Texas All-State honorable mention after collecting 45 receptions for 868 yards and 12 touchdowns. He also was on the track and field team and played soccer at Marshall High School. He committed to Memphis during his senior year.
Tahj Washington saw the field in parts of two seasons at Memphis, playing in just 4 games before taking a redshirt in 2019. The following season he played 11 games and put up some solid numbers (43 receptions for 743 yards and 6 touchdowns) before transferring to USC. In 2021, he started 11 of the 12 games for the Trojans and had 54 receptions for 602 yards and a touchdown.
Washington became a big playmaker for the Trojans in 2022, averaging 15.7 yards per catch. His 50 receptions for 785 yards and 6 touchdowns came as the #4 receiver on the USC depth chart behind Jordan Addison, Mario Williams and Brendan Rice.
In his 2023 season, Washington put up career numbers as he hauled in 59 receptions for 1,062 yards and 8 touchdowns. He averaged 18 yards per catch and was a leader in the pass catching department for the Trojans offense.