The 26-year-old Wisniewski had three goals and 27 assists in 69 regular-season games last season for a career-high 30 points. He led Anaheim in blocked shots with 102, had 129 hits and averaged 24:20 of ice time.
"We see James as a key addition to our team and we feel our fans will connect with his style of play," Islanders general manager Garth Snow said. "He is a solid puck-moving defenseman who can bring an added element of toughness to our blue line."
The Michigan native has 17 goals and 80 assists in 254 regular-season games with Chicago and Anaheim.