The 25-year-old Londoner will perform break-up banger I Wrote a Song at the pop extravaganza in Liverpool on Saturday.
But who is she, and could she win? Here's everything you need to know about Mae Muller.
Who is Mae Muller?
The singer-songwriter, whose real name is Holly Mae Muller, was born in Kentish Town, north-west London, in 1997 – the year the UK last won Eurovision.
She grew up listening to iconic artists such as Prince, Abba, Sade and Simon & Garfunkel, and has described herself as a natural performer from a young age.
"I have been an attention [seeker] since I was two," she told the Private Parts podcast earlier this year. "Every Christmas or family thing, I was like, 'I want to put on a show. Everyone sit down, I wanna sing for you'."
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Muller had her first brush with the pop industry aged just nine, when when she appeared in the music video for Mika's 2007 hit Grace Kelly. The song topped the charts for five weeks straight and was the year's third best-selling single.
Reflecting on the experience in a BBC interview, she said: "It was my favourite song ever, so that just made it even cooler, as a nine-year-old."
She was 19 when she wrote her first track, Close, which was produced by a family friend and "paid" for with wine in lieu of money. Muller uploaded her early demos to Instagram and Soundcloud, drawing influence from female stars including Gwen Stefani, Florence Welch and Lily Allen.
The pop star signed her first publishing deal when she was working in a pub in Kentish Town, and "from there it just kind of snowballed". She told Glamour: "I started getting into sessions and just making more and more music and working on improving my writing skills."
Muller released her debut EP After Hours in early 2018, and has since worked with acts including rapper Aitch and music producer and DJ Sigala.
Her breakout hit was 2021's Better Days, a collaboration with Swedish group Neiked and US rapper Polo G which went viral on TikTok, peaking at 32 on the UK charts and at 23 in the US.
Eurovision attracts a huge global TV audience but thankfully Muller already has experience playing in front of large crowds, which should help steady her nerves during the grand final.
She supported both Little Mix and One Direction's Liam Payne on tour, and has performed on The Voice US and The Tonight Show with Jimmy Fallon. She has also played at some of Britain's biggest music festivals, including Reading and Leeds and the Isle of White Festival.
Away from music, Muller will make her acting debut later this year with a role in British action-thriller Gassed Up, directed by George Amponsah.
Could she win Eurovision?
Mae Muller's I Wrote a Song is an upbeat break-up track which features tongue-in-cheek lyrics about a cheating ex-boyfriend. The song was written when she was "going through a hard time" and "wanted to feel empowered about relationships".
Over a propulsive dance beat, Muller sings: "I could've cried at home/And spent the night alone/Instead I wrote a song/I feel much better now." She penned the track with two prolific songwriters: Karen Poole, who has worked with the likes of Kylie Minogue and Lily Allen, and Brit nominee Lewis Thompson.
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Muller, the UK's first female Eurovision entry since 2018, will hope to replicate – or even surpass – the success of Sam Ryder, who finished second with his song Space Man last year. Bookmakers are offering odds of 33/1 that she take home the famous trophy.
She was unveiled as this year's hopeful in March after an "extensive search" by the BBC and music management firm TaP Music, which has counted Dua Lipa, Lana Del Rey and Ellie Goulding among its clients.
Watch: Mae Muller to perform at Eurovision 2023
Her selection as the candidate wasn't without controversy. She attracted criticism from Tory MPs after The Telegraph unearthed old tweets in which she called the Conservative Party "racist and elitist" and declared "I hate this country" in a row over free school meals.
After being accused of "vile left-wing slurs", Muller said her remarks had been taken "out of context" and said the BBC did not make her "scrub [her] personality" over the tweets. "A lot of young women follow me and it's important that they see they can have a voice," she added.
Muller will be the 26th and final performer in Saturday's contest, which will be held in Liverpool on behalf of war-torn Ukraine. "A Top 5 placing is the dream, but I'll be happy with Top 10," she told The Guardian. "I really believe in the song, the staging is amazing, the choreo is great, so it's just down to me. I can't mess it up."