Born to a family of Circassian and Turkish origin, Umar Muhayshi was member of the group of army officers called the Free Officers Movement that brought the royal regime in Libya down on 1 September 1969. He became a member of the twelve-member Libyan Revolutionary Command Council, headed by Muammar Gaddafi. He was promoted to the rank of Major after the revolution. After the establishment of the Libyan People's Court in October 1969, he represented the attorney-general at the court.