The move will save the Devils a little more than $3 million in cap space for this season. Hunter has two seasons left on his contract, which pays him $2 million per season.
"It was as much a business trade as anything," Devils General Manager Lou Lamoriello told Rich Chere of The Star-Ledger.
The move by Lamoriello will help in the efforts to re-sign restricted free agent wing Zach Parise to a long-term deal. Parise is scheduled for an arbitration hearing on Aug. 3.
Rolston, 38, recorded 14 goals and 20 assists for 34 points and 34 penalty minutes in 65 games last season. He waived the no-trade clause in his contract to join the Islanders.
"It's been a rough ride in Jersey," Rolston told The Star-Ledger. "I'm actually happy to go to a place that wants me."
Hunter, 31, joins the Devils after spending nine seasons with the Islanders' organization. He has 99 goals and 229 points in 459 career NHL contests. He was initially acquired by the Islanders from Anaheim on May 23, 2000. Hunter was selected by the Mighty Ducks' in the sixth round (No. 150 overall) in the 1998 Entry Draft.