When Nick Jonas grabbed the mike stand on Saturday, Jan. 20, he told the crowd he was going to try out his new comedy routine — it is SF Sketchfest week after all.

But while the multitalented Jonas could have probably pull it off, he came to San Francisco to sing.

“I haven’t played a show this year,” Jonas told the crowd, at AT&T’s Union Square flagship store before quickly being corrected by a friend offstage. “OK, now I’m racking my brain because maybe I misinformed you. But for story’s sake, let’s just pretend this is the first show.”

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Jonas could have said anything he wanted on that mike and the roughly 400 fans who were invited to catch the special show would have lapped it up. The event was a reward to loyal Jonas fans who won their admission via social media to an acoustic set followed by a meet-and-greet for 20 even luckier fans.

Cara Martinez drove all the way up from Los Angeles to be her friend’s plus-one. Gabriella Dematos, who lives in San Pablo, said Martinez was one of the first people she told when she found out she won access to the private show.

“I joked with her and said, ‘Too bad you can’t come up for this,’ and she texted back that she could,” Dematos said with a laugh. “Now we’re here!”

“I’ve been a fan of the Jonas Brothers since they were a thing, so it was really cool to see him that close,” Martinez said after the show.

The two 21-year-olds said they grew up with the third — and most famous — Jonas brother on television and radio throughout his career as a Disney Channel fixture and beyond.

“It was really surreal seeing him go from his ‘Camp Rock’ days and seeing him up close, and singing along with everyone else here,” Dematos said.

Softspoken during an earlier interview with The Chronicle, the 25-year-old star talked about how he’s managed to take advantage of all his skills throughout his career, particularly challenging himself with his the role Nate Kulina in th mixed martial arts-themed TV series “Kingdom.”

“I read the script and fell in love with the story — with the characters specifically,” he said of the show, which premiered on AT&T Audience Network in 2014. “It taught me a lot about who I am as an actor and a performer as a whole.”

And his acting ambitions didn’t stop when the show ended in August. He recently starred in the blockbuster family comedy “Jumanji” and wrapped up his next film, “Chaos Walking,” which is set for movie theaters next year, all while continuing to release music, dropping with his latest single, “Find You,” in September.

“As a creative person, in general, I’m setting up a lot of things to roll out over the next couple of months,” he said.

Whether his music and acting career will ever overlap in the form of a feature film musical a la “La La Land,” Jonas said he’s not totally opposed to the idea.

“So far, having the acting and the singing separate has been a good thing,” he said. “But if the right role came up and I felt it was the right project to be part of then I’d be down.”

Onstage, Jonas turned it on for fans, showering them with his adoration as he ran through a tight set of his hit songs, opening with “Levels,” then performing “Close” before his Golden Globe nominated song “Home” (which he wrote for the animated film “Ferdinand”), “Chains,” and even a fan request that had him graciously stumbling to remember a verse from “Under You.” By the time he ended his roughly 30-minute set with “Jealous,” which he admits is his favorite song to perform live, fans were pumped for more.

Unfortunately, the night had to end, leaving fans to wait for Jonas’ next tour — which actually may not be too far in the future.

To hear more from The Chronicle’s exclusive interview and watch a clip from Jonas’ live performance:

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Nick Jonas performed a special concert for a small crowd at AT&T's Union Square store in San Francisco on Saturday, Jan. 20, 2018. He spoke to The Chronicle exclusively before his performance.

Media: SFChronicle

Mariecar Mendoza is The San Francisco Chronicle’s arts content editor. Email: mmendoza@sfchronicle.com Twitter: @SFMarMendoza Instagram: @sfchronicle_scene

Check out the music video for Nick Jonas’ latest single, “Find You”: https://youtu.be/mWFaxs-KvMY