Colon, 45 in May, spent 2017 with the Atlanta Braves and Minnesota Twins, registering a 7-14 record with a 6.48 ERA and -2.2 WAR in 143.0 innings pitched.
The right-hander played with the Mets from 2014-16 and logged a 44-34 record. His name had been connected to New York at various points throughout the offseason, though general manager Sandy Alderson all but dismissed a reunion with the fan favorite.
Colon is behind just Juan Marichal for the winningest all-time pitcher hailing from the Dominican Republic. He needs just four more wins to leapfrog Marichal.
Jesse Sanchez of MLB.com was first to report the two sides were closing in on a deal.
He will earn a $1.75 million base salary should he make the big league roster, according to Evan Grant of the Dallas Morning News.