Experts from the Chicago Bomb and Arson Unit were called to investigate a backpack, which had wires sticking out of it, that had been left unattended in a flowerbed directly outside the office of Harpo Productions at around 6am local time.
Staff at the studio, where Winfrey's daily talk show is filmed, were not evacuated, reports TMZ.com.
Police gave the backpack the all-clear after discovering it was not a bomb, and removed the bag without incident three hours after they were called to the scene.