He knocked it outta the park!

A 9-year-old Harlem boy lived out many a Mets fan’s dream Monday night – by expertly calling an inning at a game.

Fourth-grader Kingston Nahm-Korn of Manhattan joined famed analysts Gary Cohen, Keith Hernandez and Ron Darling in the booth to announce the fourth inning of the Mets-Orioles game and witness some of his favorite players take the field.

“I’m most excited for the play-by-play,” Kingston said. “I think it’s very exciting.”

The boy, who attends the Calhoun School, won his spot in the booth as part of SportsNet New York’s annual Kidcaster Contest — which selects one lucky Mets fan between 9 and 12 years old who demonstrates already superb announcing abilities.

Kingston was one of several hundred spirited young baseball fans who submitted an audition video for the contest, which was sponsored by Manhattan’s Hospital for Special Surgery, known for handling many athletes.

Kingston’s video featured him calling Mets shortstop Francisco Lindor‘s walk-off, two-run double earlier this season.

The young fan didn’t waste any time in the booth Monday night, coming out of the gate to remark on Orioles’ Trevor Rogers’ pitch as “way back and foul.”

As for Mets first baseman Pete Alonso, nicknamed the “Polar Bear,” Kingston said at one point that he “isn’t too fast, but he’s faster than a real polar bear.”

One of his older mentors in the booth remarked afterward, “We’ve done this Kidcaster thing for a long time, and nobody came more ready.”

“We have had so many amazing kids, but Kingston Nahm-Korn was the best,” Darling told The Post. “Not only his play by play calls, but his humor on air and with us in the booth. Just an amazing kid.”

Kingston said the night was the culmination of more than half a decade of games with his dad – as well as years of calling practice.

The 9-year-old frequently rises around 6:30 a.m. before school to call a game while listening to Cohen, Hernandez and Darling – or turn the TV volume off altogether to call the shots by himself.

“We practiced for a year for it,” said the boy’s dad, Aaron Korn, who was at Monday night’s game along with Kingston’s mom, Kiwon Nahm — both 41.

Kingston said he oftentimes even calls the play-by-play as he simultaneously controls players’ actions on the field on the MLB The Show 18 video game.

“He practices every day – every morning he wakes up in our apartment, he does a pretend game,” his father said. 

Kingston said in the booth, “I really got started into announcers when I was like, 6 or 7 [years old]. I was like, ‘Who were those magical voices?'”

The father-son duo have been watching Mets games whenever they’re on, although Kingston frequently has to cut out early because of bedtime.

But he will get to see more of them this year — when the young caller gets his bedtime extended to 8:15 p.m.

The young Mets fan found out about his contest win last week — long after his parents had been keeping the news a secret for a month. 

“I didn’t know my dad was keeping it a secret,” Kingston said. “I was like, ‘It was probably a 12-year-old kid who did just as well as me.’ ”

His first reaction when he found out he won? 

“Is this actually happening?” he told The Post.

While Kingston could envision himself as an announcer when he gets older, his love of baseball extends further on the field, too — as a current player for the West Side Little League Mustangs and the tournament team the West Side Hawks.

He says he wants to be a baseball player when he grows up.

“That’s what I really want,” the boy said, noting that his favorite position to play is the “hot corner” at third base.

That’s not to discount his caller heroes Cohen, Hernandez and Darling, whom he gifted a hand-drawn photo of – along with himself – together at Citi Field Monday night.

“Baseball doesn’t really go well without somebody announcing,” the boy said. “It’s more entertaining. That’s why they have announcers.”

Kingston also had some tips for other aspiring callers, now that he’s achieved his major calling debut.

“As Gary, Keith and Ron said: Do it on an empty stomach, and don’t be nervous – that’s what I learned,” he said. “Just don’t be afraid.”