Charli XCX was the only act at this month’s KIIS-FM Jingle Ball to end her set as the leader of a punk band might, slamming down her microphone and stalking offstage with a scowl on her face. The British singer’s unruly exit made sense, though, given that her delightfully bratty new album “Sucker,” out this week, feels like a punk record masquerading as a big-ticket pop release.

Her second major-label disc following 2013’s dreamier “True Romance,” “Sucker” arrives at the end of a transformative year for Charli XCX, who as a songwriter scored huge hits with Icona Pop’s “I Love It” and Iggy Azalea’s “Fancy,” which also features her sneering vocals. The latter is up for a Grammy Award for record of the year, while “Boom Clap,” the lead single from “Sucker,” broke into the top 10 after it appeared in “The Fault in Our Stars.”

Yet when I met up with her recently in Huntington Park, where she’d been booked to play a high school’s homecoming dance, Charli XCX claimed not to care about all that success. What’s important to her, she insisted, is satisfying herself.

“Sucker” appeals to two audiences at once: people old enough to catch all your references to punk and to the ’90s and people young enough to appreciate your lyrics about breaking rules and hating school. You’re 22. Does that feel old or young?

I feel old, but it’s difficult to explain. In some aspects of my life – doing dumb stuff, making bad decisions, going out with the wrong people — I feel like I’m very young. But then I feel like I have another side of me where I know that I run a business. And I feel in control of that, which makes me feel adult. The music I’ve been writing recently, it’s definitely some of the most pop stuff I’ve ever written. But it’s not coming from a totally innocent, naive mind. It’s coming from someone who’s very aware.

When you were a kid listening to pop, did you get a similar sense from the artists you loved?

No. I grew up listening to the Spice Girls and Britney Spears, and I’m pretty sure that wasn’t the case with them in the beginning of their careers. But I also think that was just the time.

It was a different era.

Yeah, of course. The thing with the record I’ve made is that I don’t want to treat my audience like they’re idiots, whoever they may be – older people, younger people, whatever. Because I don’t think anyone is an idiot anymore. When I listen to music, I want something real; I don’t want something calculated. I just don’t think that works. So with this album I’ve tried to say all the things I was too afraid to say on my first record. I think that’s why my first record is kind of confusing, because I was still figuring out who I was and what I wanted to say. And with this record I’ve really just begun to realize I don’t care. And that’s very liberating. It’s allowed me to write the songs I was meant to write. That sounds like some kind of “Lion King” quote, but it’s how I feel.

The punk vibe on “Sucker” – it’s a worldview, but it’s also about heavy guitars.

I knew I wanted that from Day One.

There aren’t a ton of guitars on pop radio right now.

But that doesn’t bother me, because I haven’t made an album to get on pop radio. After the success of “I Love It,” I felt very frustrated by the new doors I’d unlocked for myself in the music industry. People were continuously asking me to replicate that song, and it was getting weird. I wanted to get some energy and some aggression out, because I didn’t feel like writing a pop song; it was all becoming very calculated in my world, writing for other people. So I went to Sweden and recorded with my friend Patrik Berger; we did “I Love It” together. He was in this band Snuffed by the Yakuza, and we did a cover of one of their songs. We listened to the Vibrators, and we made two or three other punk songs, with me just screaming.

Were you into punk when you were young?

My dad was super into it. He actually took me to see the Sex Pistols when they reformed.

What’d you think?

I thought it was terrible. But of course it was going to be terrible.

Right — it was supposed to be.

This is when Johnny Rotten had just done a butter advert for a year in the U.K. But it was cool. My dad’s a big fan of Malcolm McLaren and Vivienne Westwood. We had lots of books about punk around the house. It was definitely a part of my childhood — not a massive part, but I was aware of it.

Did it play into what you were doing on “True Romance”?

I think that album was me trying to be cool. But in hindsight I realize I was quite scared throughout the making of it.

It’s not tentative; it has plenty of attitude. But maybe that was you covering up your uncertainty.

I think the first song I wrote that was 100% me being me – not me trying to be something else – was “I Love It.” And when I wrote that and saw its success, it opened my eyes to a lot of things. Don’t get me wrong — I love “True Romance.” But I do feel like I was afraid to put myself on the line. I was 17 when I recorded a lot of those songs; I was nervous about being in the studio. It was very new and weird. It would’ve been very easy for me to go and make another album like “True Romance.” And everybody would’ve thought it was cool. But it would’ve been safe. With “Sucker,” I think I put myself on the line.