The 17-month-old can be seen in this horrifying CCTV footage staggering out into the road.
He was spotted by Mo Latif, who was on a call out but immediately jumped out of his van and raced to help.
Mo can been seen bringing the youngster to safety, before reuniting him with his grateful dad, in Whippendell, Watford on Saturday night.
Mo, 38, said: "When I saw the little boy, who was about 17 months old, on his own, I stopped my van because it was late and I wondered why he was alone.
"I couldn't believe it when he ran into the road. My instinct took over to save him from danger.
"The little boy's dad was so thankful when he was reunited with his son.
Thanks for stopping by. We welcome your comments.