The King County Board of Health was created by Metropolitan King County Council Ordinance 12098 (now superseded by 13218) in response to a state law, RCW 70.05.035, which required that the County have a single board of health by January 1, 1996. Previously the Metropolitan King County Council served as the Board of Health for King County and the Seattle City Council served as the Board of Health for Seattle.

The Board of Health is constituted as a federated body: 11 of its 13 voting members are elected officials -- 6 from the Metropolitan King County Council, 3 from the Seattle City Council and 2 from the Suburban Cities of King County. The two remaining voting members are health professionals, selected by the other members of the Board, who serve as citizen public health experts, assisting the Board to deal with complex, often technical, public health issues. A third health professional serves as a nonvoting member.

The functions of the Board are to set county-wide public health policy, enact and enforce local public health regulations, and carry out other duties of local boards of health specified in state law. These duties, which are enumerated in RCW 70.05.060, include enforcing state public health statutes, preventing and controlling the spread of infectious disease, abating nuisances and establishing fee schedules for licenses, permits and other services.

The regular meeting time of the Board of Health is the third Thursday of each month from 1:30 am to 4:30 pm. The meeting location at the Metropolitan King County Council Chambers unless otherwise specified.