Who knew Josh Groban was so funny?

Josh Groban is known for his angel-man pipes, breathtaking range, coliseum-filling baritone and the wind-beneath-my-wings anthem “You Raise Me Up.” He’s sold 30 million albums in a time when, reportedly, no one buys them. He is one of the world’s first faces of classical pop. But you already know all that, so let’s talk about the Muppets.

Earlier this month, Groban starred on ABC’s “Muppets” revival as a character named “Josh Groban” who is set up with, and promptly torn away from, Miss Piggy. (Long story.) (Actually it’s not that long: He’s part of a love triangle with Kermit, a “passionate, albeit brief affair,” Groban says when my first question is about his relationship with a fictitious puppet.) It’s actually his third Muppet-based endeavor; he had a cameo in 2014’s Tina Fey-led film “Muppets Most Wanted,” and his video for “Pure Imagination” (with Lindsey Stirling) featured the gang, in a timely, web-worthy kid-nostalgia mashup.

“I love that the Muppets are tapping into some blue humor from their older days,” Groban said last week from his New York home. “And I love that, over 15 years, I’ve got these comedic connections. The music is so super-serious, and I’m so not serious when I’m not on stage.”

He’s been not-serious a lot. You may have caught Groban on “Jimmy Kimmel Live,” singing, with glorious magnificence, the tweets of fellow comedians Kanye West and Donald Trump. (If you’ve not heard a 34-year-old with a heavenly baritone sing the phrase, “I have never seen a thin person drinking Diet Coke,” Google it, we’ll wait.) Groban played himself on “It’s Always Sunny in Philadelphia” and a vain, amplified version of himself on “Glee.” In 2012, Mindy Kaling DM’d him to offer a guest spot on “The Office.” It goes on like this.

But in case you think comedy is a side business, get this: Groban’s comic history actually predates his musical thing. As a good-natured dork in junior high, Groban asked his music teacher if he could borrow the theatre stage during free period, not for practice or vocal acrobatics or 60 minutes’ worth of scales, but to launch an improv group. “Junior high’s hell for everybody, and I was just sitting in seventh or eighth grade hating everything,” he says. “I loved improv. I loved making people laugh. It was my biggest defense against the bullies.” Before long, he was teaching six or seven kids, all “nerdy comedians” like him.

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The voice, if you can believe it, was something he kept hidden, something he mostly let fly behind closed doors, like he was hiding a treasure or an alien. “I wasn’t a YouTube kid, I wasn’t starting to get my fan base at 12 years old,” he says. “I felt like the voice was this beast that was foreign to me, so different than the guy in my head. I was such a shy kid that the voice was so not shy; it was like an animal. It took a minute for me to allow my head and my voice to be friends with each other.”

It took long enough, Groban says, that he didn’t get serious about singing until 9th or 10th grade; shortly after he graduated he had a record deal and the delightfully chaotic globetrotting acclaim that comes with the release of the beast. “I tell people you do not want to peak in junior high school. I feel like that’s how Al Bundys are made,” he says, with a laugh. “It’s good to be a nerd. It’s good to be somebody who hasn’t got it figured out yet. You want to have that wonderment, that vulnerability. It makes it that much sweeter when you finally come into your own.”

Only recently, he says, has he even felt legit as a singer. “It’s only in the past five or six years that I have the technique and experience to say, ‘OK, I’m a professional,’” he says.

Because we should probably get to the professional part, Groban is touring behind “Stages,” a collection of Broadway songs that played pivotal roles in his past (“All I Ask Of You,” for instance, was the song he auditioned for David Foster that won him his first record deal.) It covers your “Les Mis” (“Bring Him Home”), your “Carousel” (“If I Loved You” with Audra McDonald), your “Chess” (“Anthem”) and “Over the Rainbow.” If you’re a Groban fan, you’ve probably been waiting for this tour for about a decade, but Groban says the wait was deliberate.

“I didn’t want to immediately sing those songs. I wanted to establish myself first away from that world,” he says. “I felt mentally, emotionally, I needed to shelve that for a second. And I wanted to come back when I felt like I had the maturity to sing them.”

“Stages” also includes “Pure Imagination,” the swirling anthem of wonder and childlike perspective from that weird movie about the freakshow from the chocolate factory. It’s the record’s first track, and it’s the only one not from a Broadway show. But it makes sense why he put it there. “That movie strikes the ultimate balance,” he laughs. “It’s a kids’ movie, but he’s also… kind of a psychopath. I grew up watching all sorts of strange things — ‘Willy Wonka,’ ‘The Dark Crystal’ — and I’m all the better for it.” Strange things, with strange mixes. Like slaying a “Les Mis” song while dating a Muppet.

Josh Groban, Lena Hall perform 7:30 p.m. Oct. 14 at Old National Centre, 502 N. New Jersey St. Tickets are $57.50-$150; find info at joshgroban.com, ticketmaster.com