The 25-year-old, who was released by Torquay United at the end of last season, has made almost 250 career appearances.
Pearce told the official Mansfield website: "I'm excited [about signing for Mansfield]. I've trained the past few days and it's been good.
"It's good to be back in the League and also to be at a very good club. The gaffer wants to win, and so do I. I'm naturally competitive and I'll be trying to win every game in which we play."
Pearce was a trainee at Birmingham City before making his senior debut for Notts County while on loan at Meadow Lane in 2007.