The Mets finished the regular season with a record of 90–72, winning the National League East title on September 26, their first since 2006 and sixth overall.

After Colon left the game, Buddy Carlyle, filling in for an injured Jenrry Mejía, earned the save, giving the Mets a 3–1 victory.

After their opening series in Washington, former closer Jenrry Mejía was suspended 80 games for the use of stanozolol, a performance-enhancing drug (PED) banned by MLB.

Their winning streak was broken against the New York Yankees in the first game of the Subway Series, where Jacob deGrom lost to Michael Pineda.

The Mets then lost the rubber match of the series against the Yankees, their first appearance on ESPN Sunday Night Baseball since the 2013 season.

While they started the final week of May by sweeping the Phillies, they closed the month by losing a series to the Marlins, ending May with a 28–23 record.

Facing the Brewers, Jacob deGrom ended the losing streak by pitching 8 shutout innings to get the Mets a 2–0 victory and get them back to .500 returning home for a three-game set with the Cincinnati Reds.

After the game, local news pundits tore into the Wilpons' ownership of the team and GM Sandy Alderson not admitting there was a problem with the offense.

They followed this with a sweep of the Arizona Diamondbacks at Citi Field that brought the team's record to 47–42 heading into the 2015 All-Star break.

On July 29, the Mets were involved in a bizarre series of events where it was reported through various social media outlets that Wilmer Flores had been traded, along with Zack Wheeler to the Milwaukee Brewers in exchange for outfielder Carlos Gómez, as part of the Mets' desire to bring in an outfield bat.

Word spread quickly around the stadium, and eventually to Flores, who took the field in the 8th inning crying and visibly emotional.

After the game, general manager Sandy Alderson confirmed with the media that the trade had fallen through due to either medical concerns or disagreements on money, meaning Flores and Wheeler remained Mets.

The next day, Flores was on the bench while the Mets tried to put the previous night behind them, leading the San Diego Padres 7–1 in the 7th inning.

Prior to the first game, the Mets acquired outfielder Yoenis Céspedes, in a trade with the Tigers for minor league pitchers Michael Fulmer and Luis Cessa.

On August 24 against the Philadelphia Phillies, David Wright played in his first game since April 14, having missed over four months due to a hamstring injury and a career-threatening bout of spinal stenosis.

This sweep increased their division lead, which they would not relinquish, to seven games, effectively ending the chances of a Nationals comeback.

On September 26, the Mets clinched the National League East title for the first time since 2006, after defeating the Cincinnati Reds 10–2.

The Mets were the favorites to earn a home-field advantage over the Los Angeles Dodgers in the Division Series, but finished 1–5 to end the season.

Jacob deGrom pitched 4 shutout innings and the Mets took a combined no-hitter into the 8th, but Clint Robinson singled off Jon Niese to end it.

The Mets played the Los Angeles Dodgers in the 2015 National League Division Series, winning in five games.