Heads turned when Seth Meyers announced the bandleader for his new “Late Night” series on NBC: fellow comedian and “Saturday Night Live” alum Fred Armisen.

Since the show’s Feb. 25 debut, though, it’s become clear Armisen was a natural choice. The dry, offbeat funnyman, 47, brought his background as a punk drummer and his seasoned comedic chemistry with Meyers to give the fledgling show a quirky musical spirit and anchor it in something familiar.

The pitch came from “Late Night” producer Lorne Michaels, who also shepherds “Portlandia” (which meant Armisen’s obligations to the IFC series were blessed from the outset). “I’ve always wanted to write a TV theme song,” says Armisen, “and it sounded like I could put together the aesthetics without having to be there every day.”

He assembled his 8G Band, named for the studio where the show is taped, just two weeks before the test show. He texted friends Seth Jabour, Syd Butler and Eli Janney (“What are you guys doing this week?”), then found drummer Kimberly Thompson through an audition.

Armisen’s theme takes cues from a cocktail of punk songs by Big Boys, Generation X and Circus Lupus. “I wanted it to be a punk song, but I didn’t want it to be an empty punk song,” he explains. “I wanted the optimism and melody ’90s punk had, which reflects who Seth is.”

The band writes five songs for intros and guest walk-ons for every show on the morning of taping. (“Gang of Baristas” is a sample song title.) “My shortcoming as a songwriter is that I can only write in short pieces,” Armisen admits. “This fits the way I think.”

Armisen shows his funny side in regular segments where Meyers surprises him with random questions and Armisen improvises. “Seth and I have a shorthand,” he says. “We’ve been doing this for 13 years. He’s my friend and he makes me laugh — what could be better?”