The ministry is responsible for administering the health care system and providing services to the Ontario public through such programs as health insurance, drug benefits, assistive devices, care for the mentally ill, long-term care, home care, community and public health, and health promotion and disease prevention. It also regulates hospitals and nursing homes, operates psychiatric hospitals and medical laboratories, and co-ordinates emergency health services.

Created by the Public Health Act of 1882 as the first permanent health care administrative body in the province, the Ministry of Health was originally known as the Provincial Board of Health of Ontario and became the Department of Health in 1925. In 1930, the Department of Hospitals was established under the direction of the first Minister of Health; that Department became a division of the Department of Health in 1934. Insured hospital services and insured physicians' services, introduced in 1959 and 1966 respectively, were combined under the Ontario Health Insurance Plan (OHIP) in 1972. The Department of Health became the Ministry of Health in 1971, and then the Ministry of Health and Long-Term Care in June, 1999.