Molloy, 22, left Salford without playing a game for the club, and hopes to play more regularly for his new club.
"To be honest I am over the moon. It's good to get my life on track, push on and get some games under my belt," he told the club's official website.
"Rich [Agar] got in contact and said he'd seen me play a couple of times and he liked me and he wanted me before, and I've actually almost come here before and I've always thought about coming here.
"On a daily basis I want to do the best I can do it's as simple as that. I've signed here for quite a bit and I don't just want to play games, I want to be the best I can be every day I'm here."
Molloy has gone straight into the Salford squad to face Hemel Stags on Saturday.