The new eight-team league is due to begin in April 2025.
"We want to change the soccer landscape in Canada," Sinclair told TSN.
"We believe it is important that women build this league, and we are committed to developing something that is built differently, for women by women."
The Vancouver Whitecaps FC and Calgary Foothills are the first two teams to sign up to the competition, with more expected to follow suit next year.
