Born in Haverford, Pennsylvania, on February 18, 1930, Freeman was named after the man who raised his father (Theodore Cullen Donovan), as well as his maternal grandfather (Thomas Cordy Wilson). He was one of five children. Raised in Lewes, Delaware, he attended Lewes Elementary School from 1936 to 1944. His father was a farmer and his brother a carpenter, and it seemed as if he would also have a blue collar career. When Freeman and his brother were young, they saved up money so they could take plane rides. He also was a part-time worker, helping to refuel the planes and work on them. He spent most of his money on flying lessons, and with over 450 hours of flying on his training record, earned his pilot’s license by the age of 16. “I sort of grew up at the airport,” Freeman said.

Freeman played baseball and football in high school. While playing football, he was hit hard and his teeth were knocked out of alignment. He was the president of the school’s student and the local chapter of the National Honor Society; he graduated as an honors student ranked third in his class in 1948.

During that year, Freeman attended the University of Delaware at Newark to further his education. He also made some money by spotting schools of fish for local fishermen. Freeman had an operation to fix his teeth, which included grinding his teeth down, then wore braces for several months to finish the effort. He was admitted to the U.S. Naval Academy Class of 1953 on June 17, 1949. Freeman graduated from Annapolis in 1953 with a Bachelor of Science degree. In 1960, he received a Master of Science degree in aeronautical engineering from the University of Michigan.

Freeman elected to enter the U.S. Air Force and took flight training at Hondo Air Force Base and Bryan Air Force Base, Texas and at Nellis Air Force Base, Nevada. He was awarded his pilot wings in February 1955, shortly after being promoted to first lieutenant, then served in the Pacific and at George Air Force Base, California. He was promoted to captain in June 1960 while pursuing his master’s degree at the University of Michigan and then went to Edwards Air Force Base, California, in February 1960 as an aerospace engineer.

Freeman served primarily in performance flight testing and stability testing areas; he logged more than 3,300 hours flying time, including more than 2,400 hours in jet aircraft. Freeman was one of the third group of astronauts selected by NASA in October 1963 and was assigned the responsibility of aiding the development of boosters.

The Clear Lake City-County Freeman Branch Library of the Harris County Public Library and Houston Public Library systems is named in memory of Freeman. An artificial island off Long Beach is also named for him. This is one of the four “Astronaut Islands” built in Long Beach Harbor during the late 1960s as unsinkable platforms for oil drilling; the others were named Grissom, White and Chaffee, in honor of the astronauts killed in the Apollo 1 fire. A crater on the far side of the Moon was temporarily named Freeman crater by the Apollo 8 crew. The Theodore C. Freeman Highway in Lewes, Delaware, an approach road to the Cape May–Lewes Ferry which carries U.S. Route 9, was named after him by a resolution of the Delaware Senate on December 21, 1965. A plaque commemorating Freeman was unveiled at the Lewes terminal of the Cape May–Lewes Ferry on June 18, 2014, with Governor Jack Markell and family members of Freeman in attendance at the ceremony.