The eight-year-old became wedged head-first down the drain, on Ena Avenue in Dapto, about 6.30pm.
Fire and Rescue crews and ambulance paramedics were called to the scene to rescue the boy.
One paramedic climbed into the drain and spent almost half an hour trying to calm the boy while another paramedic worked to free him.
Fire and Rescue workers used specialist tools to bend the metal of the drain to release the boy’s trapped head. The boy was checked by paramedics immediately upon his release. The boy was distressed by the incident, but unharmed.
Fire and Rescue NSW station officer Darin Sullivan praised the work of the fire and ambulance officers, who worked quickly to release the eight-year-old.