McWherter's career in government began in 1968 when the successful Dresden businessman won a seat to the Tennessee House of Representatives. After just two terms, he was elected speaker of the House - a position he held longer than anyone in Tennessee history. He also made history by becoming the first person ever to serve as Speaker of the House right up until the time he assumed the duties of governor. During his legislative tenure, he served on the State Building Commission Joint Fiscal Review Committee, the Council on Pensions and Retirement, the Tennessee Agricultural and Industrial Development Commission and the State Agri-Industries Board. He was also the chairman of the House Calendar and Rules Committee, the House Finance, Ways, and Means Committee and the House General Welfare Committee.

As the 46th governor of Tennessee, he provided progressive leadership by insisting all proceedings of the House be open to the public and press. He was the original sponsor of the "sunshine law" and always adhered to an open door policy with his constituents. He opened doors to minority groups by appointing the first black committee chairman in the south and assisted women into influential leadership roles in the legislature. His 21st Century Schools education reform program launched similar programs in other states and his replacement of the Tennessee Medicaid system gained national attention. He served on several national and local councils and committees including the board of governors, Council of State Governments, the Executive Committees of the Southern Conference, the Weakley County Head Start Program and the Executive Committee of the Northwest Tennessee Economic Development District.

Governor McWherter is involved in many civic organizations and has memberships in the Elks Club, Shiners Club, Eagles Club and is a 33rd degree Scottish Rite Mason. He is also a member of the Weakley County Chamber of Commerce, the Tennessee-Arkansas-Mississippi Girl Scout Council Board, and a trustee of the University of Tennessee. He was a charter member of the Dresden Lions Club and Jaycees, and served as chairman of the Tennessee Heart Association fund raising campaign. The former governor is a member of the Methodist Church and served for 21 years in the Tennessee National Guard before retiring with the rank of major.

Following Governor McWherter's last term as chief executive in 1995, he was appointed to the Board of Governors of the United States Postal Service by President Bill Clinton and currently holds that position.