The one-year-old baby had climbed onto a window ledge during a thunderstorm in the southern Chinese province of Guangdong.
A shopkeeper opposite the building in Zhongshan City told local media the child was searching for his mother.
CCTV footage shows a passer-by moving to save the child after spotting the baby teetering near the edge of the window. With the help of another man, the baby was safely returned to its mother.
Several other people also moved to help by placing cardboard and a small sofa on the road to break the child's fall if the men failed to catch the baby.
"I didn't think too much at the time," the rescuer, Mr Li, said.
"I was just afraid of failing to catch him. Some people put down cardboard to avoid serious injuries to the baby if I failed to catch him."
