Ateman played at Oklahoma State from 2013 to 2017. As a true freshman, he played in all 13 games, recording 22 receptions for 276 yards. As a sophomore, he had 20 receptions for 268 yards. As a junior, he had 45 receptions for 766 yards and five touchdowns.[2] Ateman missed the 2016 season due to a foot injury and took a medical redshirt.[3][4] He returned from the injury and played in all 13 games in 2017, recording 59 receptions for 1,156 yards and eight touchdowns.[5]
Ateman was drafted by the Oakland Raiders in the seventh round (228th overall) of the 2018 NFL draft.[8] He was waived on September 1, 2018, and was signed to the practice squad the next day.[9][10] He was promoted to the active roster on October 23, 2018.[11] He made his NFL debut on November 18, 2018, in a Week 11 road game against the Arizona Cardinals, where he had 4 receptions for 50 yards and played a pivotal factor in the Raiders' game-winning drive, as they went on to win 23–21.[12]
On August 31, 2019, Ateman was waived by the Raiders and re-signed to the practice squad.[13][14] He was promoted to the active roster on October 5, 2019.[15] He was waived on October 8, but re-signed two days later.[16][17]
On September 5, 2020, Ateman was waived by the Raiders and signed to the practice squad the next day.[18][19] He was placed on the practice squad/injured list on September 19,[20] and activated back to the practice squad on October 21.[21] He was released on December 10, 2020,[22] and re-signed to the practice squad five days later.[23] On February 3, 2021, Ateman signed a reserve/futures contract with the Raiders.
[24]
On August 24, 2021, Ateman was waived by the Raiders.[25] He was re-signed to the practice squad on November 3.[26] He was released on November 18.
Atemwan was selected by the St. Louis Battlehawks of the XFL with the second pick in the 2023 XFL Skill Players Draft.[29] He was placed on the reserve list by the team on March 8, 2023, and activated on March 27.[30] He was released from his contract on June 1, 2023.[31]
On June 1, 2023, Ateman signed with the Buffalo Bills.[32] He was waived on August 29, 2023, and re-signed to the practice squad.[33][34] He was released on October 3, 2023.[35]