A Fire Department was established by City Charter in 1883. It provided for equipment purchases, but not for hiring of firefighters. Following the Great Fire of 1889, a professional fire department was created with five district fire stations and purchase of a fire boat. The first Fire Chief of the professional department was Gardner Kellogg who served 1890-1892 and 1895-1901. A Board of Fire Commissioners was established by the 1890 City Charter to prescribe rules and regulations for the Department. The Board's responsibilities included enforcing rules violations, and appointing the Fire Chief and all subordinate officers. The Board was abolished with passage of a new City Charter in 1896. The position of Fire Marshal was established in 1901 with responsibility for inspecting buildings to insure they were in compliance the ordinances related to building construction and fire protection. The Fire Marshal also inspects all fires and reports on the causes. The Department's mission is to curtail loss of life and property by fire through inspection and certification of building safety systems, public education, regulation of hazardous material storage, and fire suppression.

The Seattle Fire Department has operated a First Aid Unit Program on a 24-hour per day basis since 1942. As the population grew, life support systems for persons en route to the emergency room grew to be a critical issue. Providing expert life support medical care at the scene of an accident and during transport to the hospital was the goal of Seattle’s Mobile Intensive Coronary Care Unit, or Medic I program. The idea was brought to fruition by University of Washington cardiologist Leonard Cobb, working with Seattle Fire Chief Gordon Vickery. The Seattle Fire Department participated with the University of Washington School of Medicine, Harborview Medical Center, and the State of Washington Coordinating Council for Educational Occupation to bring paramedic technicians to the scene of accidents. Training began in 1969 and the first Medic One call was on March 7,1970. Paramedics are first employed as firefighters. Services were expanded throughout King County in 1976, and other counties in Washington State began adopting their own Medic One programs. As of 2009 there were six Medic One programs in King County; Seattle Medic One is operated by the Seattle Fire Department and funded by the city’s general fund.

The response system of 911, medical dispatch, basic life support, and paramedic advanced life support has an international reputation for excellence in pre-hospital emergency care. The program was featured on "60 Minutes," and correspondent Morley Safer stated, “If you have to have a heart attack, have it in Seattle.” The Medic One Foundation grew out of donations for the program and became an independent foundation; it became a tax-exempt organization in 1975. The Foundation receives and distributes contributions on behalf of the Medic I program.

The Medic II Program started in 1971 and provides training classes in cardiopulmonary resuscitation (CPR) and choking techniques. It is based on research showing that prompt bystander CPR more than doubles a patient’s chances of becoming a long-term survivor. Classes are taught by firefighters on their own time; they are compensated out of a donated budget.