As the mid-season All-Star break approached, team management talked about limiting Harvey's innings to ensure his pitching health.
On May 7, while pitching with a severe nosebleed Harvey retired the first 20 Chicago White Sox batters he faced until Alex Ríos broke up the perfect game with an infield single.
Harvey left the game after nine innings, having surrendered only the one hit, as the Mets won in 10 innings.
In his major league debut on July 26, 2012, against the Arizona Diamondbacks, Harvey set a new club record with 11 strikeouts while earning his first career victory.
Harvey had a breakout season in 2013, being selected to play in his first Major League Baseball All-Star Game.
It was later announced that Harvey had finished tied for 4th in the Cy Young Award, losing to Los Angeles Dodgers pitcher Clayton Kershaw.
On October 22, 2013, Harvey underwent successful Tommy John surgery to replace the partially torn ulnar collateral ligament in his right elbow. James Andrews performed the operation in Gulf Breeze, Florida.
In 2011, Harvey's first professional season in the Mets minor-league system, he split time between the single-A St. In the Eastern League with Binghamton, he went 5–3 with a 4.53 ERA and 64 strikeouts in 59.2 innings. That performance earned him IL Mid-Season All-Star honors.
Harvey also pitched in the 2011 All-Star Futures Game, recording a save for the winning U. His strong pitching, plus injuries to major leaguers Mike Pelfrey and Dillon Gee, put him in contention for the fifth spot in the Mets rotation.
After an injury to staff ace Johan Santana and replacements to the Mets' major-league rotation failed to turn in quality starts, general manager Sandy Alderson and Mets manager Terry Collins backtracked and decided to promote Harvey to the majors, ending his stay with the Bisons with a 7–5 record and 3.68 ERA.