On July 1, 2016, Ladd signed as a free agent to a seven-year, $38.5 million contract with the New York Islanders. Despite hoping to replace the Islanders' losses of Kyle Okposo and Frans Nielsen to free agency, Ladd struggled in his first few games with the Islanders, going his first five games without a point and his first 12 games without a goal. The subpar performance of Ladd and other Islanders players led to the mid-season firing of head coach Jack Capuano on January 17, 2017. At the time of the firing, Ladd had 8 goals and 4 assists in 40 games. But under new head coach Doug Weight, Ladd's performance increased, with Ladd scoring 15 goals in the next 38 games, and finished the season with 23 goals, 8 assists, and 31 points in 78 games played. On March 26, 2019, it was announced that Ladd, after appearing in 26 games through the season, would miss the remainder of the 2018–19 season due to torn ACL.