In 1939 Brooks married Henry Lowington Blakely, Jr. They had two children: Henry Lowington Blakely III, born on October 10, 1940; and Nora Blakely, born in 1951.
From mid-1961 to late-1964, Henry III served in the U.S. Marine Corps, first at Marine Corps Recruit Depot San Diego and then at Marine Corps Air Station Kaneohe Bay. During this time, Brooks mentored his fiancée, Kathleen Hardiman, today known as anthropologist Kathleen Rand Reed, in writing poetry. Upon his return, Blakely and Hardiman married in 1965. Brooks had so enjoyed the mentoring relationship that she began to engage more frequently in that role with the new generation of young black poets.