General manager Scott Howson announced the move on Wednesday.
The 34-year-old Martinek, a 10-year NHL veteran, had 21 goals and 82 assists with 272 penalty minutes in 453 games with the New York Islanders. Last season, he had three goals and 13 assists with 35 penalty minutes and a 20:50 average ice time in 64 games. He missed most of the 2009-10 campaign due to a knee injury.
The Islanders' 12th pick, No. 228 overall, in the 1999 draft, Martinek, a native of the Czech Republic, made his NHL debut in the 2001-02 season. He also represented his homeland in the 2000 and 2001 World Championships, helping to capture back-to-back gold medals.