Adrienne Batra told the Canadian Broadcasting Corp. Ford was resting at home and would see a urologist Friday.
"He is in good spirits as some of the pain has subsided," Batra said.
Kidney stones are very common -- accounting for many thousands of emergency room visits every year. They can be very painful but are usually treated without surgery."
The Toronto Star reported the 41-year-old mayor entered Sunnybrook Health Sciences Centre at lunchtime to be treated for a "medium-sized" kidney stone and was discharged about 5:30 p.m.
Asked how he was doing, a groggy-sounding Ford told the newspaper by cellphone, "Well, I've been better." Ford has had kidney stones in the past.
Dr. Mike Feldman said standard protocol was planned for the mayor -- treat the pain and wait to see if the stone passes on its own.
"I'm not sure if the stone has passed but I know that his pain is gone," Feldman said.