Mexican welterweight Jeanette Zacarias Zapata, 18, was knocked down in the fourth round against Marie Pier Houle at the GVM Gala International in Montreal on Saturday.
She appeared to have a seizure after being dazed by a left uppercut and a right hook and was taken to hospital.
The fight promoter, Yvon Michel, announced the news on Thursday.
"It is with great sadness and torment that we learned, from a representative of her family, that Jeanette Zacarias Zapata passed away this afternoon at 3:45 pm," his statement read.
