The New York native joined the Islanders on Friday after posting 14 goals and 18 assists in 82 games last season with the Florida Panthers. He will earn a total of $2.7 million.
"The addition of Marty solidifies our center position," Islanders general manager Garth Snow said.
Before his stint with Florida, Reasoner played two years with the Atlanta Thrashers and had 18 goals and 47 points in 159 games. Reasoner spent the majority of his time between 2001-08 with the Edmonton Oilers, and was also a member of the Boston Bruins.
He had 45 goals and 76 assists in 351 games with Edmonton.
The Islanders also announced that they agreed to terms with 18-year-old forward Kirill Kabanov on a three-year, entry-level contract. Kabanov set career highs this season with 11 goals and 28 points in 39 games with Moncton and Lewiston in the Quebec Major Junior Hockey League.