Robert Lovett was born in Huntsville, Texas, on September 14, 1895. He graduated from Yale in 1919 after serving in World War I. Lovett studied briefly at Harvard's graduate schools of law and business but joined his father's banking firm in 1921. During his work with international business and industry in the 1920s and 1930s, Lovett became familiar with European military strengths and capabilities and was offered the post of special assistant to Undersecretary of the Navy James Forrestal in 1940.

In 1941, he became the assistant secretary of war for air and held this post until 1945, when he resigned and resumed his banking career. Lovett returned to government service in 1947, however, as undersecretary of state. He was deeply involved in early Cold War planning, including the formation of NATO. In 1949, when Secretary of State George Marshall resigned, Lovett did the same.

He later returned as deputy secretary of defense when Marshall became secretary of defense in 1950. In September 1951, Lovett took over Marshall's slot following the latter's resignation. As defense secretary, Lovett initiated a coordinated department-wide defense budget. He returned to banking when President Truman left office in 1953.

During the Kennedy administration, Lovett served as a presidential advisor and continued to sit on numerous high-level committees through the 1960s. He died on May 7, 1986, in Locust Valley, New York.