The accordion has always been a part of Alex Meixner's life. But even he could not have predicted it would make him an advertising star.

It all began with his band's performance at a Wisconsin summer festival in 2015. That gig, which Mr. Meixner said was almost canceled because of rain, turned out to be a turning point in his career, leading to his role as the familiar face of Hormel pepperoni. His quirky one-man band characterization is now in its second year.

After leading the pepperoni category with limited marketing, Hormel and longtime creative agency BBDO Minneapolis wanted to pep up the business. Hormel had not advertised any pepperoni products on TV since 2011. They decided a one-man pep band could show people how pepperoni peps up everyday life, and were getting ready to hold auditions. After someone close to the agency saw Mr. Meixner's band in Wisconsin, BBDO Minneapolis reached out to him to audition.

Mr. Meixner's father had a band, a recording studio and a record shop that was also a mail-order business for items including polka recordings when the family lived in Pennsylvania. They relocated to the Orlando, Fla., area when his father got a job as a musician at Epcot Center. Mr. Meixner went on to graduate from Ithaca College with trumpet performance and music education degrees, though the accordion is the instrument he is most associated with to this day. "You couldn't be an accordion major," he said.

He expected to land in academia. As it turned out, "There was a resurgence. The word 'polka' became less of a stigma and more of a unique oddity, for lack of a better term." He started to see younger people coming to shows he played with his father. And he kept performing, later on with his own eponymous band, which now does about 120 shows per year.

When BBDO first reached out, Mr. Meixner thought one of his friends might be playing an elaborate prank. But it was real. He quickly needed an audition tape of him playing "My Sharona," so in between gigs, his saxophone player shot some video on an iPhone.

"He's actually the sole audition, the first and only audition," said Scott Schraufnagel, BBDO's group account director on Hormel refrigerated meat products. "When we saw it, we knew it was the right fit for Hormel pepperoni."

Soon, representatives came to Florida, where Mr. Meixner lives, to fit him for the mix of one-man band instruments he carries in the spots. In the fall of 2015, he was flown to Los Angeles for production. He put on "the contraption," as he sometimes calls it, and he wondered if he could play it.

"I had two hours by myself with the contraption and it happened," he said. "I've spent years in conservatory training and all kinds of different lessons and those were two of the most challenging hours. It was as stressful as an academic senior recital because if this doesn't work, there's a lot of stuff on the line for everybody that has worked on this for the last two months."

In mid-January 2016, "My Pepperona," the brand's take on "My Sharona," began airing. The timing was critical, as Hormel and BBDO wanted to take advantage of a key selling season for pepperoni, with the Super Bowl and other gatherings taking place.

Within the first week, Google searches for "Hormel pepperoni" and just "pepperoni" were climbing. Similar spikes occurred again in January 2017, when the brand's "Dance" spot starring Mr. Meixner began running.

The campaign is delivering in a category that tends to be promoted with discounts. Baseline sales, those excluding any kinds of offers, rose more than 3% during last year's run, said Mr. Schraufnagel.

"When the commercial first aired, my social media exploded," Mr. Meixner said. Soon after, he was at a swim meet with his daughters, and some kids came over to ask if he was the guy who does the pizza commercials, showing how closely connected the foods are. Earlier this month, a man next to him on an airplane recognized Mr. Meixner from TV. (He was not familiar to a woman sitting nearby^-—a vegan without a TV.)

"Overwhelmingly, the reactions have been positive, it's fun, it's light-hearted," Mr. Meixner said. "There's nothing controversial about it. It's a great thing to be involved in something that people are having fun with."

Before BBDO reached out to him, Mr. Meixner's only commercial work was performing in a studio on tracks that were a backdrop for a Ford F-150 radio spot, he said. He never thought he would be on screen. For now, Mr. Meixner said he is not soliciting any other work. He said he is "very happy" with his relationship with Hormel and BBDO and looks forward to growing that role with them.

Meanwhile, his band keeps traveling across the country, often for German festivals and Oktoberfest occasions. Along with expected standards, like the "Chicken Dance," the band plays anything from Austrian folk songs, jazz and country to its rendition of Ozzy Osbourne's "Crazy Train," Mr. Meixner said. "And, of course, now there's inclusion of Hormel pepperoni anthems."

The TV campaign ran for about six weeks in early 2016, and this year it is running for about 10 weeks. Along with BBDO on creative, Hormel works with PHD on media.

Social media continues year-round with paid content and plenty of fans posting their own videos. The content from fans includes babies giggling when they hear one of the songs and a man singing the tune in his shower. Someone posted a video in which Mr. Meixner crashes a poetry reading in a repeating loop that lasts an hour, which has more than 20,000 views on YouTube.

"It definitely is an earworm and that was the intention," Mr. Schraufnagel said.

Chances are, more work featuring the one-man pep band will come out in time for the early 2018 pepperoni-selling season.