It happened around 5:30 p.m. on Monday near the intersection of S. Kilson Drive and Edinger Avenue in Santa Ana.
Sarah Tran, who shared her dashcam video, said she stopped her car, ran out and grabbed the child and brought him to safety.
"He was determined to go into the middle of the road. I was so afraid of cars just not seeing him because he's so small and bolting into him," she said.
It is not yet clear where the parents of the child were at the time of the incident.