The 22-year-old attacker joins from fellow WSL side Tottenham Hotspur, following previous spells with PSG and Valerenga — where Celin secured a domestic double in 2020.
For her country, Celin has represented Norway at all playing levels from under-16, making 21 full international appearances to date.
Celin Bizet:
"I'm very excited to take this next step in my career, and sign for such a great club as Manchester United. I cannot wait to pull on the famous red shirt and create winning moments in front of these wonderful fans.