The first incident occurred at a TD Bank at 807 Broadview Ave., just north of Danforth Avenue, shortly after 2:30 p.m. ET.
Police said a suspect armed with a gun entered the bank and demanded money. No one was injured during the robbery and the man was able to flee with an undisclosed amount of money.
There was only one customer in the bank at time.
Police describe the alleged thief as male, white and 5'8" with a slim build. He was wearing a black mesh shirt with something white underneath.
At around the same time, police were dispatched to a separate armed hold-up at the BMO branch at 100 King St. W., near the Bay Street intersection.
Police said the male suspect was black, bald with some white hair and wearing a blue-short-sleeved shirt with Winnipeg on the front.
It's not clear whether the suspect made off with any money. A black handgun was used in the robbery.
Later in the afternoon, officers in 52 Division responded to a third robbery at a TD Bank on the corner of Bay Street and Bloor Street at 3:45 p.m. after a suspect entered the branch wearing a motorcycle helmet.
Witnesses leaving the bank told CBC News the suspect acted calmly and when he ran off police gave chase.
Police confirmed that a man had been arrested in the incident and that it appeared to be unrelated to the earlier incident at the TD branch.