Miller was born in Lockport, New York. He attended the University of Notre Dame and Albany Law School. He served in the United States Army during World War II, and later helped prosecute German war criminals at the Nuremberg trials. Miller was appointed district attorney of Niagara County, New York in 1948, by Governor Thomas E. Dewey. Miller served in the United States House of Representatives from 1951 to 1965 and was Republican national chairman from 1961 to 1964.