Hayes was at first a Whig, then joined the new Republican party in the 1850s because of their stance against the expansion of slavery into the western territories. He entered politics in 1858 when the Cincinnati City Council appointed him to fill a vacancy as city solicitor. He was elected to the position in 1859, but lost a bid for reelection in 1861. During the Civil War he rose from major to major-general while serving in the Twenty-third Ohio Volunteer Infantry.

Elected to an open Congressional seat in 1865 and reelected the next year, Hayes generally backed the Reconstruction policies of the Radical Republicans and favored the impeachment of President Andrew Johnson. As chair of the Joint Committee on the Library, he worked to transform the Library of Congress into a world-class facility. Resigning from Congress in 1867, he ran for governor of Ohio on a platform that endorsed black manhood suffrage. He defeated Allen Thurman, then won reelection in 1869 against another Democratic challenger, George Pendleton.

Governor Hayes was instrumental in Ohio's ratification of the Fifteenth Amendment and its establishment of The Ohio State University. Furthermore, he reduced the state debt by twenty percent, encouraged civil service reform, and advocated better treatment of inmates in prisons and mental institutions and of the indigent. He declined to run for a third term, but accepted a nomination for Congress in 1872. He was defeated and returned to his private law practice.

With the onset of economic depression in 1873, the Democratic party scored political victories in Ohio, Congress, and across the nation. In 1875 Republicans convinced Hayes to seek a third term as governor, and he won by a slim margin over incumbent Democratic governor William Allen. Hayes' victory made him a contender for the Republican presidential nomination in 1876, but he faced a field of formidable candidates led by James Blaine, former Speaker of the House. Trailing Blaine and three other candidates through four ballots, Hayes finally received the nomination on the seventh ballot, narrowing edging out Blaine.

Difficult obstacles lay on Hayes's road to the White House: economic depression, Grant administration corruption, Southern resistance to Republican voters, and a Democratic rival, Samuel Tilden, who had a reputation as a reformer. In fact, Tilden triumphed in the popular vote, but disputed tallies from Florida, Louisiana, and South Carolina, plus a dispute over the credentials of an Oregon elector, created a national crisis. Congress created a bi-partisan commission, consisting of members of the House, Senate, and Supreme Court, to adjudicate the matter. All the contested electoral ballots were granted to Hayes, allowing him to win the election by one electoral vote.

Hayes took office with many Americans believing he had been elected by fraud, with a Democratic majority in the House (and also in the Senate after 1878), and with his own party divided into rival and often hostile factions. With diligence and integrity the new president was able to overcome some of those impediments. He was assisted by talented cabinet members, especially Secretary of State William Evarts, Treasury Secretary John Sherman, and Interior Secretary Carl Schurz. Hayes formally ended Reconstruction by removing the remaining federal troops from the South; he advanced the cause of civil service reform, laying the foundation for the latter passage of the Pendleton Act (1883); and he saw to the enforcement of the Resumption of Specie Act, which placed the United States back on the gold standard. His pragmatic, measured response to the Great Railroad Strike of 1877-remaining neutral between strikers and management, and only allowing the limited use of federal troops to keep the peace when state or local officials requested assistance-probably saved lives and property. By the end of his term, economic prosperity had returned. A supporter of a single-term presidency, he declined to run for reelection.

In retirement, Hayes continued to speak out on public issues, supporting veterans' pensions and the federal regulation of business (e.g., the Interstate Commerce Act). Committed to the diffusion and progress of education, he served as trustee of the Peabody Fund, a charity aimed at educating poor Southern blacks and whites, and as first president of the Slater Fund, established to aid the education of blacks. He urged Congress to allocate monies to supplement educational funding in poor states and territories. He was on the board of trustees of The Ohio State University, Ohio Wesleyan University, and Western Reserve University. He also served as president of the National Prison Association, and opposed the death penalty.