"We welcome Myles back to our organisation with open arms", said Browns general manager Andrew Berry.
The reinstatement will allow Garrett to return to the team and participate in pre-season workouts that begin in April.
Garrett's suspension is the longest for a single behavior in league history. Garrett has been remorseful since the incident and Monday he met with Commissioner Roger Goodell and league officials in NY.
The incident came at the end of the Browns' 21-7 home victory over the Steelers, following a scrum on the ground during which Rudolph appeared to get a hand on Garrett's helmet and kick him in the groin. "We look forward to having his strong positive presence back as a teammate, player and person in our community".
The 24-year-old's offense - "removing the helmet of an opponent and using the helmet as a weapon", per National Football League rules - was unsettling even for a sport in which violence is a mainstay.
The ensuing melee led to fines of $250,000 for each club and suspensions of two games for Steelers center Maurkice Pouncey and one game to Browns defensive tackle Larry Ogunjobi. Rudolph tried to pull off Garrett's helmet but couldn't.
Fines ranged from $3,507 for most of the players involved, to Rudolph's $50,000 - a stiffer penalty than the $35,096 that usually comes with a first offense for fighting.
Garrett, 23, had apologised for his "selfish and unacceptable" actions.