Aged just 19, the star has racked up seven hits in the last 14 months, including the tropical pop smash Lush Life, which spent more than a year on the charts.
Along the way, she's collaborated with Tinie Tempah and sung the official anthem of Euro 2016, but the highlight of her year was supporting Beyonce at Wembley Stadium.
"It was the best show on a tour I've ever seen. Wembley's such an incredible stadium. It's definitely one of the stadiums I want to stand on and have my own tour, one day."
Although she's already scored a number one single and album in her home country, Zara is starting from scratch in the UK - and releases her debut album, So Good, this week.
Outgoing and dynamic, she talked the BBC through her career to date. Here's everything you need to know (and a few things you probably didn't) about Sweden's latest pop sensation.
Writing on her Swedish-language website two years ago, the 19-year-old revealed she frequently has episodes of sleep paralysis.
"Oh my God, it's scary!" she tells the BBC. "Basically, you wake up and you literally cannot move. Your brain is active, but your body is not yet awake.
"It's weird. It lasts half a minute maybe - but it kind of feels like you're trapped there for half an hour.
"I get it a lot when I'm stressed out, or when I have a lot of things going on."
But Zara says there's an upside, too. Often, as she falls asleep, she's overcome by a sense of tremendous wellbeing (to paraphrase a certain Blur song).
"It's like a wave comes over me. Energy is just vibrating through your body and it's awesome."
In 2008, Zara entered Talang Sverige - Sweden's version of Britain's Got Talent - mainly because there was no age restriction, unlike X Factor or Swedish Idol.
Singing a heavily-accented, but vocally powerful, version of Celine Dion's My Heart Will Go On, she won the contest, and its 500,000 krona (Â£42,600) prize.
"I sounded like a little guinea pig!" she laughs. But, incredibly, the contest led to nothing.
"Nobody really wanted to sign me, which I was devastated about," she says. "I was like, 'oh my gosh, my career's over and it hasn't even started yet!'
"I didn't really want to do anything with Nickelodeon or Disney, so I just went back to school."
The break may have saved her. Rather than becoming a novelty act, washed up before she was a teenager, Zara re-emerged as a bona fide pop artist on her 15th birthday, with an EP that turned people's heads.
"When I released the first song, a lot of the people didn't even recognise me," she says. "And the people that did were like, 'Oh my gosh, it's her!'
"So in Sweden, the talent show is like super-irrelevant. And that's great because usually it's very hard to wipe off that kind of Got Talent stain.
"It just stays on you - but it didn't for me."
...As we discovered when we played a game of "So Good or So Bad?" with Zara (watch above)
When Zara released Lush Life in January last year, a lot of people thought it was Rihanna's comeback single.
"I don't know where it comes from but even my mom is like, 'You sound like Rihanna,'" says the singer.
"I was very confused because I'd never really listened to her until pretty recently. It's not a bad comparison to have but I'm never going to be Rihanna, and I'm not trying to be.
From the moment Zara fired up her Instagram, pulled a condom over her leg and called out guys who "think they're too big to wear protection", it was clear Zara wouldn't be sticking to the record company script.
Since then, she's voiced her support for Kesha - who is suing famed record producer Dr Luke for alleged sexual assault - and engaged in a war of words with R&B star Chris Brown, calling him "a sexist, homophobic, transphobic trash".
"That's who I am," says the star. "I don't really have a 'vision' of who I want people to see me as.
"I just post whatever I feel like."
Larsson was born in Stockholm at the tail end of the 1990s, moving to the suburbs when her younger sister Hanna was born.
She was always singing - showing off to her parents' dinner-party guests; and serenading "ladies on the subway, when I was like three".
But she didn't come from a musical family. Far from it.
"My dad was a military man, working in Navy intelligence," she says, "so I know he can keep secrets, definitely."
While the exact nature of his job remains classified, Larsson swears he was the model parent.
"He's great and he's funny. You can ask him whatever and he always has the answer. Even if he doesn't, he will never admit it. So we had a lot of debates and discussions. That's the reason why I'm interested in everything.
"Now he's actually studying again - he wants to be a professor in war science."
Potential boyfriends beware.
Zara's breakout hit in the UK was Never Forget You - a duet with British producer MNEK that was written in just two hours.
"We work really well together," she marvels. "It's just no question marks. I feel very relaxed and honest and open with him. "
They collaborated again on Ain't My Fault, a sassy, sexy club track that became Zara's fifth top 20 hit, late last year.
"We wrote it in five minutes," says Zara, "Originally, it was about me stealing someone else's man. I was saying, 'It ain't my fault that you're not cute enough for him.'"
But after submitting the song to her record label, the singer had second thoughts.
"I was just like, 'Wait, hold up, I can't sing this'. It just didn't feel right. It felt like I'd broken the girl code, and I didn't want to do that."
As a child, Zara attended the Royal Swedish Ballet School.
"I was very flexible," she says. "It really taught me a lot about discipline and how to use my body. But these days I'm about as flexible as aâ€¦ erm, a safe!"
In fact, she's so out of shape that a brief session with her personal trainer ended in disaster.
"I ran 200 metres and my trainer said, 'That was a great job, you ran pretty fast'.
"I said, 'I know!' so he told me to do it a second time. And when I came back, I threw up."
"I'm on my way to becoming a true performer," the star wrote shortly after singing Lush Life on The Voice UK last year. So, does she not consider herself a fully-qualified pop phenomenon yet?
"You're never finished," she says.
"My inspiration for performing is Beyonce. I don't think Beyonce  ever wakes up and thinks, 'Oh great I'm Beyonce, I'm just going to chill today.'
"She wants to be better, she wants to do bigger things and she wants to keep on evolving.
"That's what makes her great, and that's what I want to do."
Zara Larsson's album, So Good, is out now on Epic Records; as is her collaboration with Clean Bandit, Symphony. She also plays the Isle of Wight Festival in June.
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In Sweden, she's been a star since she was 10 - but Zara Larsson has her eyes set on global domination.