Gillaspia was drafted by the Houston Texans in the seventh round, 220th overall, of the 2019 NFL Draft. He played 12 snaps on offense during the regular season. In the AFC wild card game, Gillaspia made a crucial block on two Bills defenders to set up Deshaun Watson for a touchdown run in a 22-19 overtime victory. In Week 3 of the 2020 regular season, Cullen Gillaspia caught his first career reception, against the Pittsburgh Steelers. It went for 6 yards.
