In 2003–04, Ronning signed with the New York Islanders, mostly playing as a powerplay specialist, recording 24 points in 40 games played. As the NHL lockout suspended play, Ronning was inactive the following season. When the NHL resumed, Ronning announced his decision to retire on February 15, 2006. Cliff Ronning was involved in two of the most notable games of Patrick Roy's career. He played against Roy in the 1982 Air Canada Cup midget tournament. Ronning's team beat Roy's Sainte-Foy Gouverneurs, and it was the last game of Roy's midget career. On April 22, 2003, Ronning played for the Minnesota Wild, and played in Roy's final NHL playoff game.