Durham Regional Police say the collision occurred on Goodwood Road, west of Lakeridge Road, shortly after 12:30 p.m. Saturday.
Witnesses told police that a motorcycle and a black Nissan SUV were heading eastbound, when a silver Lexus travelling westbound crossed the centre line.
Police say the Lexus struck the motorcycle, which the Toronto woman was driving.
She was thrown from her motorcycle and struck by the SUV. Police say she died at the scene.
The collision remains under investigation.