The shuttle apparently struck the woman near Geary and Leavenworth streets just after 12:20 p.m., San Francisco police Sgt. Michael Andraychak said.
The woman is believed to be between 40 and 65 years old, police and fire officials said.
The driver had turned the shuttle left from northbound Leavenworth onto Geary, where the front of the vehicle struck the woman as she crossed Geary, Andraychak said.
No arrests have been made and no one else was injured.
Streets near the crash site were temporarily closed but have since reopened, Andraychak said.