Kastelli was the capital of the Province of Pediada until 1994 when the municipality of Kastelli was formed through a voluntary initiative by the surrounding communities. Since 1998 it has operated officially within the framework of  Kapodistrias law.

The municipal offices are situated in Kastelli, operating from September 2003 in the renovated building of the old Gymnasium (High School) of Kastelli.  In the municipal building there are today all the administrative services, plus the Citizen Service Centre and the offices of Kastelli's municipal enterprise.