The City of Brentwood was incorporated on April 15, 1969 and operates under the Council/Manager form of government.

The Board of Commissioners (informally, the "City Commission"), the city's chief policy-making body, enacts laws known as ordinances, and sets policies and takes other formal actions through resolutions.  The Commission adopts the Capital Improvements Program and Annual Budget each year.  The City Manager serves as the city's chief administrative officer and sees to it that the Commission's programs are implemented.

The Mayor and Commission Members are elected at-large by the citizens of Brentwood to serve four-year terms.  The Commission oversees a variety of volunteer advisory boards and commissions that assist with specific city-related issues.  The advisory board members are appointed by the City Commission, with the exception of the Planning Commission, which is appointed by the Mayor.