Osawatomie is a city of the second-class with a Mayor-Council-Manager form of government. The citizens elect the Mayor and City Council.  The City Manager is hired on contract by the City Council.

The city is divided into four wards and each ward has two Councilmembers representing them on the Governing Body. Business and policy-making is conducted by the Governing Body with the Mayor presiding, who has the privilege of casting a vote in order to eliminate a tie.

The Mayor is elected every odd year for a term of two years. Each Councilmember's term is two years. Each ward staggers their tenure of office so that one representative is elected every year from each ward.