Washington appeared in 10 games, five as a starter, as a true freshman at Illinois in 2019, posting 11 receptions for 132 yards.[3] He then had 10 catches for 106 yards in 2020.[4] He entered the NCAA transfer portal and transferred to the Wake Forest Demon Deacons in 2021, but had second thoughts during spring practice and re-entered the transfer portal, returning to Illinois and being granted an eligibility waiver by the NCAA.[5] He ended the 2021 season with 21 catches for 294 yards.[6] During the season, he caught the game-winning two-point conversion in the team's 20–18 nine-overtime win over the Penn State Nittany Lions, which set a record for most overtimes; Washington's gloves from the game were put on display in the College Football Hall of Fame.[7]
In 2022, Washington played 13 games, three as a starter, and had 31 catches for 306 yards.[8] He had his best year as a senior in 2023, recording 49 catches for 670 yards and four touchdowns.[9] He ended his collegiate career having appeared in 55 games while totaling 122 receptions for 1,508 yards and four touchdowns.[10] He was invited to the East–West Shrine Bowl.[11]