Noah Syndergaard was the complete package Thursday.

After stumbling through his previous three starts, the Mets right-hander rebounded with a getaway day special: a four-hit shutout with 10 strikeouts in which he homered for the game’s only run in a 1-0 victory over the Reds at Citi Field.

“I felt like I was pretty close to rock bottom, so it was kind of an adapt-or-die kind of situation,” said Syndergaard, whose ERA dropped from 6.35 to 5.02. “It feels like a huge weight has been lifted off my shoulders.”

Syndergaard became the first pitcher in Mets history to throw a complete game and homer for the only run. And Thursday was only the seventh such occurrence in major league history, according to MLB.com.

The Mets shrugged off a ninth-inning loss from a night earlier, when Jose Iglesias homered against Edwin Diaz for the game’s only run, to finish with a split in the four-game series.

Syndergaard received an ovation as he returned to the mound in the ninth for the final three outs. Overall he retired 10 of the final 11 batters he faced, giving a recently overtaxed bullpen a breather.

“The main thing is [Syndergaard] said, ‘Enough is enough,’ ” manager Mickey Callaway said. “He knows he had to be better than what he was and he kind of stated that, he worked hard in between, he went out there and got it done.”

Clean shaven with his hair down for the first time this season — he had been using a “man bun” — Syndergaard is ready to chart a new course. In each of his past three starts, Syndergaard had pitched only five innings and allowed at least four earned runs.

“I am never having a beard again,” Syndergaard said. “I had to cut five inches off it the other day. I felt very Rapunzel like.”

Derek Dietrich singled in the ninth against Syndergaard and pinch-runner Michael Lorenzen stole second, but Yasiel Puig struck out looking to end the game.

It came a night after Jacob deGrom gave the Mets seven scoreless innings to snap a recent skid. Jason Vargas was also effective in a start Tuesday, allowing one run over 5 ¹/₃ innings. Steven Matz will try to keep the momentum rolling when he pitches Friday night in Milwaukee.

“The last time through the rotation, you can’t ask for more,” Callaway said. “I think our hitters are starting to realize that, our team is starting to realize that and we have a good opportunity here to go on this road trip and keep it going and start making some headway.

“We have got to feed off what we have been doing as a pitching staff the last five days and get things going.”

Syndergaard’s blast into the left-field seats leading off the third gave the Mets their only run. The homer was Syndergaard’s second this season and the sixth of his career. DeGrom and Zack Wheeler have also homered this season, giving Mets pitchers four home runs — tying the franchise record set in 2016.

But Syndergaard doesn’t necessarily oppose the idea of the DH in the National League.

“Really both sides, because I like hitting, it’s fun, it keeps things relaxed when I am out there pitching,” Syndergaard said. “On the other side a lot of the opposing pitchers don’t know how to swing the bat all that well, so I just see it as an opportunity to get an extra couple of strikeouts throughout the game.”

Tyler Mahle limited the Mets to one run on four hits with seven strikeouts over five innings. The right-hander retired eight of the nine batters he faced following Syndergaard’s homer. Pete Alonso’s walk in the sixth gave the Mets their only base runner in their final three at-bats.