Matsuzaka, 32, signed a deal with the Mets, the team confirmed Thursday. He will start Friday against the Detroit Tigers.
Matsuzaka was 5-8 with a 3.92 ERA in 19 starts for Triple-A Columbus in the Cleveland Indians organization this season. He was granted his release earlier this week.
The tentative plan is to have Matsuzaka and right-hander Carlos Torres both see action in the series opener against Detroit, with Matt Harvey staying on an extra day of rest Saturday. Matsuzaka threw 85 pitches Monday for Triple-A Columbus, so sharing the duty would lessen the workload of coming back on short rest.
The Mets have lost two starting pitchers to the disabled list in recent days.
Right-hander Jeremy Hefner indicated he is headed toward Tommy John surgery, although he will seek a second opinion Monday from Dr. James Andrews in Birmingham, Ala.
Right-hander Jenrry Mejia will undergo season-ending surgery to remove a bone spur in his pitching elbow in the next week to 10 days.
The Mets temporarily had planned to plug their rotation void by using Torres, who was listed as the starter for Friday's game at Citi Field.
The team does not want to promote its top pitching prospects at Triple-A Las Vegas, Rafael Montero and Jacob deGrom, because both are facing team-imposed innings caps. In Montero's case, he does not need to be added to the 40-man roster this offseason for Rule 5 protection, either.