The 74-year-old British music legend - whose countless hits include "Maggie May" and "I Don't Want To Talk About It" - talked about his illness at a fundraising event in England for the Prostate Project over the weekend.
Stewart told the crowd he was diagnosed during a routine check up in 2016 - and was given the all-clear in July of this year.
The rock star is urging other men to get regular check-ups.
The World Health Organization says prostate cancer is the fourth most common type of cancer in the world, with some 1.3 million cases in 2018.