Modeled after the federal government, the State of Illinois consists of three governmental branches: executive, legislative, and judicial. The executive branch is led by the governor, the legislative by the Illinois General Assembly (House of Representatives and State Senate) and the judicial branch by the supreme court.

Along with nearly 47% of all cities with populations of 5,000 or more, the Peoria, Illinois government has adopted the Council-Manager form of government with a City Manager appointed by the City Council. Usually by contract, the City Manager (currently Charles Randy Oliver) serves the City Council and is responsible for supervising operations and implementing policies. The mayor (currently Jim Ardis) acts as a City Council member and presiding officer.

The City of Peoria has multiple departments to oversee and facilitate the infrastructure, economics, public services, government, and more:

Peoria City Departments:

Peoria City Employees Credit Union

City Manager's Office

Economic Development

Emergency Communication Center

Equal Opportunity Office

Finance Department

Human Resources Department

Information Systems Department

Inspections Department

Legal Department

Planning and Growth Management Department

Peoria Public Service:

Peoria Fire Department

Peoria Police Department

Other City of Peoria Services:

Board of Election Commissioners

Peoria Animal Welfare Shelter (PAWS)

Peoria Cares