The fire service were called in after the unlucky child trapped his arm in a metal tube of the frame just before 6pm.
It took just under an hour to free the boy from the frame in Lauderdale Park, Dunbar in East Lothian.
Firefighters from the town had to use two heavy tools to cut through pipework to free the child, who avoided a trip to hospital.
An angle grinder and an automatic saw were used to cut through the climbing frame.
A spokeswoman for Lothian and Borders Fire and Rescue Service said: “A four-year-old child’s arm was stuck in a climbing frame.
“Firefighters used a grinder and a reciprocating saw to free him.
“The child was checked over by ambulance crews at the scene but did not have to go to hospital.”