The team didn't disclose terms of the deal announced Wednesday.
O'Brien suited up for Nashville last season, scoring two goals and dishing out seven assists in 80 games. He also played in all 12 playoff games last spring for the Predators, who were eliminated by the Vancouver Canucks in the conference semifinals.
The 27-year O'Brien was originally taken by Anaheim in the eighth round of the 2003 draft. He has appeared in games with Anaheim, Tampa Bay, Vancouver and Nashville over his career.