The incident happened in Roodegate, Basildon just after 1.30pm after a group of young men found what they thought were toy handcuffs.
Basildon sub officer Warren Breeze said: "The boy was out with a group of friends when they came across a set of handcuffs which were half locked on the fence post and the other half dangling open.
"The boy thought they were toy handcuffs and locked himself in them for a joke and it was then that he discovered they were proper police handcuffs and he was locked in.
"They called us and we used a power saw to cut the handcuff which was on the post so that the boy could walk to the police station for them to unlock the other cuff; but just as we had finished a patrol car turned up with the keys.
"This boy found himself in a bit of a fix and all of his mates were laughing at him.
"We have no idea how the handcuffs ended up being there like that."