Miller was born in Defiance, Ohio. He attended University of Notre Dame and received his Bachelor of Laws degree in 1914. He joined the Ohio National Guard and served in France during World War I. After the war, Miller began practing law in Cleveland. In 1928, he was elected county prosecutor and had a hand in defeating the city manager plan. He defeated Daniel E. Morgan for mayor in 1931, becoming the first Democrat to serve as the city's mayor since Newton D. Baker. In his tenure, Miller reduced expenditures to cope with the misery brought by the Great Depression. He was defeated by returning Cleveland politician and former mayor, Harry L. Davis, when he attempted to run for reelection in 1933.
In 1938, Miller became chairman of the Cuyahoga County Democratic party. As chairman he succeeded in attracting African American voters which allowed the Democrats to elect mayors for thirty years and obtain a Democratic majority in council. Miller resigned as chairman in 1964.