Cowser signed with the Oakland Raiders after going undrafted in the 2016 NFL Draft.
On September 3, 2016, he was waived/injured by the Raiders and placed on injured reserve.
On September 10, he was released from the Raiders' injured reserve.
He was signed to the practice squad on October 4, 2016.
He was promoted to the active roster on November 26, 2016.

On September 1, 2018, Cowser was waived by the Raiders.
He was re-signed to the practice squad on October 22, 2018.
He was promoted to the active roster on October 30, 2018.
He was waived on November 5, 2018 and was re-signed to the practice squad.
He was waived on November 13, 2018 and later re-signed to the practice squad.

Cowser signed a reserve/future contract with the Raiders on January 1, 2019.
He was waived during final roster cuts on August 30, 2019.
Cowser signed with the Oakland Raiders after going undrafted in the 2016 NFL Draft. On September 3, 2016, he was waived/injured by the Raiders and placed on injured reserve. On September 10, he was released from the Raiders' injured reserve. He was signed to the practice squad on October 4, 2016. He was promoted to the active roster on November 26, 2016.
On September 1, 2018, Cowser was waived by the Raiders. He was re-signed to the practice squad on October 22, 2018. He was promoted to the active roster on October 30, 2018. He was waived on November 5, 2018 and was re-signed to the practice squad. He was waived on November 13, 2018 and later re-signed to the practice squad.
Cowser signed a reserve/future contract with the Raiders on January 1, 2019. He was waived during final roster cuts on August 30, 2019.
James Cowser