The 40-year-old Colon went 18-6 with a 2.65 ERA in 30 starts for the Oakland Athletics this past season. He finished second in the American League in ERA and sixth in Cy Young voting.
Colon was suspended 50 games in 2012 for violating MLB's performance-enhancing drug policy. He will join Jonathon Niese, Zack Wheeler and Dillon Gee in the rotation, helping to offset the loss of ace Matt Harvey, who is due to miss 2014 while recovering from Tommy John surgery.
"We have lots of young talent, but we don't want to rely on it entirely," Mets general manager Sandy Alderson said Thursday. "And it also provides us the kind of depth that we're going to need through the course of the season. So adding experienced pitching, whether at the top end of a rotation or elsewhere, was an important factor for us."
Alderson indicated the Mets also will search for a fifth starter from outside the organization this offseason.