Vick, 35, will now serve as Ben Roethlisberger's backup in Pittsburgh.
"So blessed to be apart of such a prestigious franchise!" Vick posted on Instagram.
The Broncos will play the Steelers on the road this season in Week 15 (full schedule here). It's not guaranteed that Vick will play in that game, though some have speculated that Pittsburgh will use him for two-point conversion attempts.
Vick will become the No. 2 QB in for the Steelers, which gives him a shot to see the field next season. Roethlisberger has only ever played 16 games three times during his 11-year career, as minor injuries have slowed him down nearly every season.
During his 12-year career, Vick has thrown for 22,093 yards and 131 touchdowns while adding 6,010 yards and 36 more touchdowns on the ground.
Vick is 1-1 against the Broncos all-time, throwing for 500 yards and two touchdowns in those games. He's also rushed for 156 yards against Denver.