The incident occurred outside the store located on the 400 block of North McKinley Avenue around 9 p.m.
Investigators say the suspect approached the 34-year-old victim as she exited her car and asked her for spare change.
When she reached into her car to get the money, police say the man brandished a knife and forced her to drive to a secluded area in Riverside County where he sexually assaulted her.
At about 4 a.m. Friday, nearly seven hours later, the suspect made her drop him off near La Sierra And Indiana avenues. He allegedly exited the car and fled on foot.
The victim reported the incident to police on Sunday evening. The suspect was described as a white man, possibly in his 40s, standing around 5 feet 7 inches with a slender build. He was last seen wearing jean pants, a grey pullover hooded sweatshirt and a black baseball cap.
The Walmart in Corona is open 24 hours. A security guard patrols the lot day and night, but customers say panhandling at the location isn't unusual.
The investigation is ongoing. Anyone with information regarding the case or who recognizes the suspect was urged to contact the Corona Police Department at (951) 736-2330 or Detective Mario Hernandez at (951) 279-3659.