Toronto police say the assault happened in his vehicle.
A 25-year-old woman hailed an Uber vehicle in the Yonge Street and Eglinton Avenue area to drive to her home in the Lawrence Avenue West and Avenue Road area, say police.
The driver allegedly sexually assaulted her inside the vehicle.
The driver, listed in the Uber app under the name "Amritpal", is described by police as 26 to 30 years old, with short black spiked hair a chin strap-style beard.
Police are asking anyone with information to contact police at 416-808-3200, Crime Stoppers anonymously at 416-222-TIPS (8477), online at www.222tips.com, text TOR and your message to CRIMES (274637).