De Haan had five goals and 20 assists this past season, both career highs, and was headed for arbitration as a restricted free agent.
The 26-year-old will see his role with the Islanders rise this season, with Travis Hamonic having been traded to Calgary.
He won a silver medal with Team Canada at the 2017 world championships back in May.
The Ottawa native was a first-round pick of the Islanders (12th overall) in 2009.
“Calvin is a home-grown product of the organization and has developed into one of our top defencemen during his time with the organization,” Islanders general manager Garth Snow said in a release. “He plays important minutes for our club and we’re excited to have him back for one more year.”