Handley attended public schools in La Porte and in 1932 received a Bachelor of Arts degree from Indiana University, Bloomington, where he majored in economics, minored in political science, and was involved in campus politics. A friend and roommate at the Delta Tau Delta fraternity house was William E. Jenner, later U. S. senator from Indiana.
Following graduation and a brief stay in Washington, Handley returned home to assist in the family business, the Rustic Hickory Furniture Company. The Great Depression took a toll on the enterprise, however, and he spent two years shoveling coal on a delivery truck to help make ends meet. Attempts to revive the company failed, and when the family was forced to close the business toward the end of the 1930s, Handley became a sales representative for a North Carolina furniture company.
Throughout these years Handley's interest in politics grew. He organized the La Porte County Young Republicans in 1932 and ran unsuccessfully for the state senate in 1936. He was elected four years later and attended the 1941 legislative session in Indianapolis.
Following American entry into World War II, he resigned his state senate seat and entered the United States Army. Initially a second lieutenant because of college ROTC training, he was promoted to first lieutenant after further instruction at Fort Benning, Georgia. He served with the Eighty-fifth Infantry Division as a company executive officer and battalion commander. While he was attending school at Fort Leavenworth, Kansas, his unit was shipped overseas. Despite requests to join his outfit, Handley was given stateside commands training infantry replacements. He was discharged in 1946 with the rank of lieutenant colonel.
After the war Handley returned to La Porte and resumed his career in furniture sales; he also became associated with commercial and industrial film studios in Chicago and Hollywood. In 1948, he was elected to the state senate, and four years later he was nominated as lieutenant governor on the ticket headed by George N. Craig. Handley defeated his Democratic opponent, E. Spencer Walton, by 230, 000 votes. As lieutenant governor Handley presided over the state senate and served as commissioner of agriculture and of commerce and industry. He viewed himself as Indiana's leading salesman and made presentations across the country to attract new industry to the state. Often joking that when he became commissioner of agriculture, he "didn't know a gilt from a quilt, " he educated himself by becoming active with 4-H clubs and attending thirty to thirty-five county fairs each year. At the same time he was accumulating political IOU's and building name recognition that served him well when he ran for governor in 1956.
There had not been a major tax increase in Indiana since the 1930s, and Handley believed that the state faced a financial crisis. He thus campaigned on a platform of raising some state taxes, an unlikely position for an Indiana Republican. He won nevertheless, defeating Ralph Tucker, mayor of Terre Haute, by 227, 000 votes. He later admitted that Dwight Eisenhower's presidential coattails were a help. Handley convinced the 1957 legislature to enact 50-percent increases in gasoline and gross income taxes (the latter including a provision for payroll withholding), an action that won him the nickname "High Tax Harold. " He always resented the sobriquet, noting that the state was desperate for revenue and that he also oversaw the repeal of most of the state property tax. He refused to take any position on a controversial right-to-work law, fearful that doing so would jeopardize his legislative program. When both houses of the general assembly (controlled by Republicans) passed the measure, Handley let it become law without his signature - thus earning the enmity of the state's labor unions.
In 1959, when Democrats controlled the house of representatives, he proposed a more modest legislative program, referring to it later as a "flag-waving session. " He underestimated the importance of a school reorganization act passed that year with his support, a law that rapidly transformed public education in the state by forcing consolidation of small township schools.
In 1958, Handley ran for the U. S. Senate seat being vacated by his friend Jenner. The campaign was conducted amid controversy over whether the state constitution prohibited a sitting governor from seeking another office. Although the state supreme court upheld his candidacy, lingering resentment over the tax increases, the right-to-work law, and a highway department scandal related to the Craig administration in which he had served contributed to his sound defeat by Democratic candidate, Vance Hartke.
Returning to private life in early 1961, Handley cofounded a successful advertising and public relations firm in Indianapolis.
Handley's political orientation manifested itself in his attitude toward federal aid. Although he did not oppose all such programs (matching funds for highways, for example), in general he took a dim view of federal "paternalism. " He once told a U. S. Chamber of Commerce luncheon that Washington bureaucrats had "substituted the image of a mother hen for the American eagle, " and in an interview with Nation's Business in May 1950 he complained that the ability of state and local officials to respond to their constituents' needs was being curtailed by a "supercentralized government now far beyond the effective control of American taxpayers. "
Handley served on the boards of several philanthropic groups, most notably as chair of the Comprehensive Mental Health Committee for Central Indiana and as a director of the United Fund of Greater Indianapolis.
He died at Rawlins, Wyoming, while on vacation.
Handley was an active member of the Republican Party.
Handley was an affable man whose sartorial trademark was a bow tie with white polka dots.
A popular speaker, he remained in demand nationwide. He was, in the words of an editorial at the time of his death, "an extremely articulate spokesman for the conservative cause, " and a sketch that appeared during his tenure as governor observed that he stood "squarely in the tradition of conservative Republican politics in his state. "
During the war, while stationed in the Mojave Desert, Handley met Barbara Jean Winterble, a Red Cross psychiatric social worker assigned to the field hospital there. They married on February 17, 1944, and had two children.