Born in Helsinki, he emigrated with his family to the United States in 1923. He initially studied sculpture at the Académie de la Grande Chaumiére in Paris (1929/30). He began practicing architecture in the U.S. with his father, Eliel, in 1936 after receiving a B.A. at Yale University in 1934. Their collaboration won the first prize of the Smithsonian Institution Gallery of Art competition in 1939. In 1937, he began a collaboration with Charles Eames which culminated in a series of highly progressive and prize-winning furniture designs for The Museum of Modern Art´s 1940 "Organic Design in Home Furnishings" competition. He later produced several highly successful furniture designs for Knoll International. His greatest architectural project was the TWA terminal at John F. Kennedy Airport in New York.

Saarinen went on to gain world wide recognition for winning the design competition for the Jefferson National Expansion Memorial in St. Louis, later known as the Gateway Arch. His design of the Arch was chosen on February 18, 1948 as the winner of the Jefferson National Expansion Memorial Design Competition. He was awarded $50,000 for his winning design.