Sankey became a judge of the High Court, King's Bench Division, in 1914. He was appointed a Lord Justice of Appeal in 1928. He was raised to the peerage as Baron Sankey, of Moreton in the County of Gloucester, in 1929 on being appointed Lord Chancellor in Ramsay MacDonald's Labour government. He was one of the few Labour politicians to follow MacDonald into the National Government in 1931, and served as Lord Chancellor until 1935, when Stanley Baldwin re-entered office. In 1932 he was created Viscount Sankey, of Moreton in the County of Gloucester.