The young boy was walking on San Bruno Avenue near Gaven Street just after 4:00 am when he was spotted by a man driving to work.
The man stopped to pick him up and then called 911. Responding officers searched a nearby building and located the apartment the boy wandered away from.
The Good Samaritan is a father of three from Daly City.
"I'd do what any parent would, touched my heart, you know. Plus I nearly hit him on top of that. Hopefully, everything's good now. He's back home, safe and warm again," said Mark Formalejo, the man who found the boy.
Police are not filing any charges against the toddler's parents, but they did make sure the doors to the boy's apartment were properly locked.