But here she was at the biggest music awards on the planet, among the biggest names in pop. Here she was sitting with co-nominee Gotye, who had roped her in to be the opposing voice on his Somebody That I Used to Know. They recorded it in his Melbourne bedroom in early 2011.
Two years and 10 million copies later the song, with its "featuring Kimbra" credit was on two Grammy nominations - Best Pop Duo/Group Performance and the second-to-top-award of the night, Record of the Year. Other nominees in the latter included mega-hits like the Black Keys' Lonely Boy, Taylor Swift's We Are Never Ever Getting Back Together and We Are Young by fun.
So Kimbra didn't think they had much chance. Especially as unlike those fellow nominees they hadn't been asked to play the song on the night. "I kinda took that as a sign that maybe we weren't going to be main players in the awards ... but we were stoked to be at an award ceremony for the first time and we were able to relax and not have to worry about a performance."
Turns out she was wrong.
Somebody won Gotye and Kimbra both Grammys. As well, Gotye - the nom du pop of Belgian-Aussie Wally De Backer - also won Best Alternative Album making it three out of three for him. And it was Prince who presented them with Record of the Year.
"The fact that he gave us an award. I have no words ... it's crazy."
It might be a Gotye-penned song, but that award for best duo/group pop performance meant she could take some satisfaction for her role in how it sounded and its success.
"That one in particular honours the performance element of it, so that feels particularly special."
Kimbra is the fourth New Zealander to win a Grammy after jazz arranger Alan Broadbent and musical comedy duo Flight of the Conchords.
And so far as what it all means for her career, Kimbra says the Grammys are a sign she's on the right track, not the goal itself.
"Look, it's just a massive acknowledgement and exciting. It's a platform for me to continue making music and have a much larger audience, you know? I think both me and Wally feel that now. And we feel a great sense of lifting our game in the music that we make next ... and being fearless about it and doing something different. So that's cool."
As the cab nears her hotel, she laughs that she's keen to get out of that fairytale dress before any further celebrating. The gown - by Perth designer Jaime Lee Major - turned out to be prophetic. The colour set off the golden glow of Kimbra's trophies while wearing a garment encrusted with 2kg of freshwater pearls ... well, if the Grammys haven't already, it sure does say: The world is her oyster.
