Allen Bristol Aylesworth was born on November 27th, 1854, in Newburgh, Ontario, the son of John Bell Aylesworth, a farmer, and Catherine Bristol. After attending Newburgh Academy, Aylesworth enrolled in University College at the University of Toronto, graduating with a Bachelor of Arts and the Prince of Wales Prize in 1874, and a Master of Arts in 1875. He was admitted as a student-at-law by the Law Society of Upper Canada in 1874, and articled under William Glenholme Falconbridge at Harrison, Osler & Moss before his call to the Bar in 1878. Aylesworth practiced law in Toronto with that firm, which underwent many names changes before becoming Aylesworth, Garden, Stuart & Thompson. He was made a Queen's Counsel for Ontario in 1889 and for Canada in 1890. Though offered an appointment to the Supreme Court of Canada in 1903, Aylesworth instead accepted a position as a member of the Alaska Boundary Tribunal. In 1904, he unsuccessfully stood as a Liberal candidate for Durham, Ontario, in the federal election but was elected to the House of Commons in a 1905 by-election for York North and re-elected in 1908. During his time in Parliament, Aylesworth served as Minister of Labour and Postmaster General (1905-1906) and Minister of Justice and Attorney General (1906-1911) before retiring from politics in 1911. In 1910, Aylesworth served as the Canadian and British agent in the North Atlantic Coast Fisheries Arbitration at The Hague, and for his efforts there he was knighted (KCMG) in 1911. In addition to his legal practice and political career, Aylesworth was an elected bencher of the Law Society of Upper Canada between 1891 and 1906 before becoming an ex-officio bencher. He was also a senator of the University of Toronto and a vice-president of its alumni association. In 1923, Aylesworth retired from legal practice after his appointment to the Senate by William Lyon Mackenzie King. He served in that position until his death in Toronto on February 13th, 1952, at the age of 97.