Mason, the youngest son of Isaac and Mary de Jarnette Mason, was born in Sayreton. He graduated from Huntsville College (now Alabama A&M University) in 1891 and served briefly as principal of the public school in Calera. He resigned to study medicine, and earned his M.D. at the Meharry Medical School in Nashville, Tennessee in 1895. He began practicing in Birmingham that year, and later completed a special course in surgery at the University of Edinburgh, Scotland in 1899. He was appointed assistant city physician for nearly eight years. He organized the Provident Hospital and later the Home Hospital at the Alabama Orphans and Old Folks' Home, which was renamed the George C. Hall Hospital. He served as president of the Alabama Medical Association and helped organized the National Medical, Dental and Pharmaceutical Association.
Mason was a vice-president of the Alabama Penny Savings Bank from 1897 to 1908 and founded the Prudential Savings Bank in 1910. The two institutions merged in 1915. He was a trustee of 16th Street Baptist Church, involved in the project to erect their current building in 1911, and was also involved in locating Central Alabama College in Mason City.
Mason was also a real estate investor, owning property in Birmingham and New York. He served as an at-large delegate at the 1908 and 1912 Republican National Conventions. He was a prominent member of the Knights of Pythias of Alabama, and served as endowment treasurer for more than 20 years, spanning numerous controversies within the organization. He was awarded an honorary doctorate from Wilberforce University in Ohio in 1923.
He married the former Alice Nelson of Greensboro on June 28, 1898. They had four children: Vivian, Ellariz, Ulysses Jr, and Alice. He had two more daughters, Dorothy and Gloria with his second wife, the former Elsie Downs, whom he married in 1916. Ulysses Jr graduated from the University of Chicago Medical School and went on to establish the first fully-integrated hospital in Cleveland, Ohio.
Mason moved to Chicago late in life, taking residence in a three-story townhouse at 4816 Prairie Avenue South in the Bronzeville neighborhood. He died there in 1933 after a long illness. He was buried in that city.
- Boothe, Charles Octavius (1895) Cyclopedia of the Colored Baptists of Alabama: Their Leaders and Their Work Birmingham: Alabama Publishing Co., p. 230–231, via Documenting the American South (2001) University of North Carolina Library
- "Advance in Birmingham" (October 18, 1913) Indianapolis Recorder
- "Dr. U. G. Mason Claimed by Death" (October 7, 1933) The Birmingham Reporter, p. 1
- Beckford, Geraldine Rhoades (2013) Biographical Dictionary of American Physicians of African Ancestry, 1800-1920. Cherry Hill, New Jersey: Africana Homestead Legacy Publishers ISBN 1937622185