Rosario signed a minor-league contract with the Mets on Tuesday, Pat Ragazzo of SI.com reports.
Rosario elected free agency Sunday after being DFA'd by Atlanta, and he didn't have to wait long for another opportunity. The 32-year-old has taken a major step back at the plate this season, slashing just .175/.215/.316 across 319 plate appearances between Atlanta and Washington, though he could claim a bench spot in New York if he's able to turn things around with Triple-A Syracuse.