Cox, 24, went undrafted out of Old Dominion in 2019 and caught on with the Chargers but was later waived. Denver signed him to a futures contract but he was among their final roster cuts. The following day the team added him to their practice squad.
Cox was promoted to the active roster at the end of 2020 but was eventually waived again. He signed another futures contract with the Broncos in January of 2021.
In 2020, Cox appeared in seven games for the Broncos, making one start at fullback.