In March 1910, Bentham became a member of the executive of the Women's Labour League. She stood unsuccessfully as the Labour candidate for Kensington Borough Council in 1909, and London County Council in 1910, before being elected a member of Kensington Borough Council in 1912, representing the ward of Golborne, a position she held until 1925. After World War I she was appointed a magistrate, one of the first women in the role, working in the children's courts and serving on the Metropolitan Asylums Board.