Following in the footsteps of artists such as Adele, Keane, Jessie J and Sam Smith to scoop the prize, which started in 2003.
Sigrid has already had a great year, although she has yet to break through to the upper echelons on the UK music charts.
Her track Don’t Kill My Vibe, released early in 2017, reached No62 in the UK, and her recent track Strangers was also playlisted by the likes of Radio 1.
Her upcoming UK tour is already sold out.
Hearing news of her win in front of BBC journalist Lizo Mzimba, she had a tear in her eye as she said simply: “What?!”
Asked what the victory means to her, she added: “Of course you’re asking that question right when I’m about to cry!
“How would you describe that? It means a lot.”
Sigrid – full name Sigrid Solbakk Raabe – is a Norwegian singer and songwriter, aged 21.
Other contenders in the Sound Of… poll have included Rex Orange County (second place), IAMDDB (third), Khalid (fourth) and Pale Waves (fifth).
Last year’s winner was Ray BLK, while Jack Garratt won in 2016.
Years and Years, HAIM, Ellie Goulding, Little Boots, Mika, Corinne Bailey Rae and Michael Kiwanuka are among the other winners in bygone years.
50 Cent was the first ever winner back in 2013.