CHICAGO — Melisa Young — better known in the pop world as Kid Sister — has just gotten off a plane and stepped inside her North Side apartment for the first time in weeks.

“It’s nice to be home,” Young says with a laugh as she picks up the phone to start this interview, her last bit of business before she goes to sleep. She says her apartment is cold, so the interview is done under the covers of her bed with her coat on.

She’s just completed an exhausting month of promoting her debut album, “Ultraviolet” (Downtown/Universal), one of the most talked-about albums of the year with its cutting-edge merger of hip-hop, dance music and pop.

“Last night, I had dinner with Questlove of the Roots, and he played a little DJ set in the meatpacking district (in New York),” she says. “It was very yuppie, but a lot of fun. I danced around in my underwear.”

For some performers, an underwear dance might connote something provocative. But Young makes it sound anything but, more like a bunch of girlfriends enjoying themselves at a slumber party. “I am a nerd,” she says. “I’m not a celebrity.

Yet in the past few years, she’s become one of the brightest new faces in club music. She’s collaborated with artists such as Kanye West, Pharrell Williams and Gnarls Barkley’s Cee-Lo Green, all of whom requested to work with her. She made her first network TV appearance a few weeks ago on “Late Night With Jimmy Fallon,” showing not a hint of stage fright as she frolicked in the audience while performing an energetic version of her single “Right Hand Hi.” Already a veteran of main-stage appearances at festivals such as Coachella in California and Lollapalooza in Chicago, she is now preparing for a new year of heavy touring worldwide.

Remembering her blue-collar upbringing

Through it all, Young remains unfazed, a budding pop star who still remembers very well where she came from: a blue-collar upbringing in suburban Markham, Ill., and years of trying to squeeze music making between shifts clerking at retail stores. At one point, she was holding down three jobs and catching catnaps on breaks while fending off warning notices from utility companies because she couldn’t keep up with her bill payments.

“I don’t think I realized this was my full-time job until about nine months ago,” says Young, 29, of her music career. “I was going to release my album last year, and then I took it back to work on it some more because it wasn’t exactly the way I wanted it. That’s when it sunk in: This is what I do. It took a long time. I’d always played it off as, ‘These are my little songs; it’s not a big deal. It’s just a hobby.’”

Melisa Young played a number of lead roles in high school musicals, and she briefly lived out her childhood dream of becoming a performer. Those plans were deferred as she studied film while attending Columbia College in Chicago.

She worked behind the scenes on a couple of Hollywood movies, doing everything from fetching coffee for Sigourney Weaver to building props. She didn’t have enough money to move to New York to find steady work, and she found the movie industry even less lucrative in Chicago. A “tedious and repetitive” stint as an assistant on an ill-fated reality TV show for $100 a day convinced her she was in the wrong business.

Meanwhile, her brother was ripping it up on the DJ and dance scene in Chicago with his friend Curt Cameruci. Their inventive mash-ups of hip-hop, pop, rock and electronic music brought a measure of underground fame in the duo Flosstradamus. Melisa Young started tagging along to their parties, bringing her friends to dance the night away.

“I was broke, and my brother was making money doing music, doing something fun,” Young says. “I took notice of that.”

Melisa Young started rapping and became a regular presence at Flosstradamus shows. In 2006, she met one of her brother’s friends in the business, Alain Macklovitch, aka A-Trak, who was the DJ for rising star Kanye West. “I was working on some new sounds, moving from hip-hop productions to messing around with a lot more clubby, up-tempo tracks with synths and electronic influences,” Macklovitch says.

“She was just starting out, but that was her background: house and hip-hop. She had an understanding of new sounds bubbling up in club music that a lot of rappers were not aware of. But she also had the potential to be a real rapper, not just someone who raps over tracks just to make her friends laugh, so it was cool to test out my stuff with a new artist who didn’t have any preconceptions about what this could be. She just did it naturally.”

Establishing her sound and persona

Macklovitch launched his record label, Fool’s Gold, with Kid Sister’s debut single, “Damn Girl.” The follow-up, “Control,” began to establish her sound and persona. In her lyrics Young used her girl-next-door up-bringing as inspiration rather than mimicking the extravagant fantasies and boasts of mainstream hip-hop.

“When my old friends hear my lyrics, they say, ‘Girl, that sounds just like you,’” she says. “That’s because those lyrics come from conversations I’ve had or little phrases I’d use in everyday life.”

Her 2007 breakthrough hit, the sassy, instantly catchy “Pro Nails,” was homemade too. “A-Trak made that beat in my kitchen that smelled of hot dogs when I was living with six people,” Josh Young says with a laugh.

The hot-dog-flavored beat — even Melisa Young found it “a little weird at first” — was a turning point, especially when Kanye West paid it the ultimate compliment.

“Kanye heard it on the tour bus, and he really liked that hook and the chord progression,” Macklovitch says. “He was really into the idea of the indie club scene and electronic music before anyone else in hip-hop, and he saw the potential. He’d go to my parties while we were on tour, and he’d see the kids reacting to this music, and he’d say, ‘I need in on this.’”

West added a rap verse to “Pro Nails” and participated in the low-budget video shoot. The song, launched off Young’s MySpace site, became an Internet hit, and the video aired on MTV. Pretty soon, Melisa Young was fielding calls from record-label executives offering deals. She eventually signed with New York-based Downtown Records, home of Gnarls Barkley, Santigold and Mos Def.