The teenager tried to escape to Austria after robbing the bank in the Bavarian town of Bad Fuessing, southern Germany, but was arrested before he could reach the border.
The boy went into the bank last week brandishing a fake gun and shouted "Hold-up!".
Frightened staff handed over some money to him before the teen made his getaway.
The boy then raced off on his bicycle, and was chased by a witness in a car, 'RTE News' reported.
The teen was arrested by police while trying to cross the border into Austria.
He admitted to robbing the bank using a toy gun.