Washington Jr. played at Buffalo from 2021 to 2023, recording 1,119 yards on 263 carries and 10 touchdowns over 27 games. After the 2023 season, he entered the transfer portal and transferred to New Mexico State University. In his lone season at New Mexico State in 2024, he played in 12 games and rushed 157 times for 725 yards and eight touchdowns. After the season, Washington Jr. entered the portal again and transferred to the University of Arkansas. He spent the 2025 season as the starting running back for Arkansas.