As one of the most popular referees and administrators in the early history of J173basketball, O'Brien helped to mold the modern game. O'Brien was known as a snappy dresser with lots of style. He officiated in the New York State League, the Inter-State League, and the Connecticut State League through 1918. Seven years later, O'Brien began a new career, organizing several early professional basketball leagues. In 1925, he founded Metropolitan Basketball League, which featured the Original Celtics. From 1928 to 1953 he served as president, and later as chairman of the board, for the American Basketball League.

Died December 9, 1967