McNulty, 30, who teams back up with Dale boss Keith Hill after the pair worked together at Barnsley, has put pen to paper on a two-year contract.
Hill told the club’s official website: “I have been chasing Jim since I came back to the football club, he’s a good defender at a very good age.
“He’s a player I know very well because I took him to Barnsley from Brighton and I believe his best years are maybe in front of him.
“We have a very good player, a very strong player and he knows me and how I want to play the game from a defensive and footballing point of view.
“I know Jim’s pleased to be here and I’m pleased to have finally recruited him.”
Liverpool-born McNulty started out at Wrexham and had spells at Macclesfield, Stockport and Brighton before being signed by Hill for Barnsley in July 2011.
He joined Bury in January 2014 but was released last month after making 30 appearances during their promotion-winning campaign.