Damage was done to the roof and drainage, causing leaks inside the bandstand.
The vandals broke drainpipes which caused a leak from the roof.
Graffiti and ant-climb paint was found 'smeared' on newly painted walls and doors.
Hinckley and Bosworth Borough Council said the work was done in anticipation of the return of public concerts and entertainment
They have issued an appeal to find the culprits.
Last week police confirmed they would be undertaking 'proactive patrols' around Hinckley's parks due to large groups of teenagers fighting.