The collision happened in the 3600 block of Jamboree Road, where the Bellavie Nail Lounge and the 949 Salon, a beauty supply store, were damaged, according to police.
The injured female employee was on a break and sitting on a concrete pillar outside the building when the vehicle struck the pillar and then crashed into the businesses, said John Nguyen, manager of the nail salon.
The driver of the vehicle was identified only as a woman. She was conscious and breathing after the impact, investigators said, adding that alcohol was not believed to be a factor.
Nguyen said the motorist apparently got the accelerator and brake pedals mixed up, and was apologetic after the incident.
The cause of the crash is under investigation.