Keith Robertson was born on May 9, 1914 in Dows, Iowa. He joined the Navy in 1931, and served as a radioman on a destroyer. Later, he attended the United States Naval Academy, graduating with a B.S. degree. He attributed his initial decision to study at the Academy to a "fanatical aversion to washing dishes." He said, "When I discovered that midshipmen at the United States Naval Academy did not wash dishes but were gentlemen by act of Congress, I promptly applied for entrance." Robertson served in World War II as captain of a destroyer. He was awarded five battle stars. He retired from the service as a captain in the United States Naval Reserve.

Robertson published his first book, Ticktock and Jim, in 1948. His writing career spanned 40 years. As a member of the Rutgers University Council on Children's Literature, he was active in encouraging aspiring authors.

He was married to Elizabeth Woodburn Robertson, a rare-book dealer, and had four children. He died of cancer at his home in Hopewell, New Jersey on September 23, 1991, aged 77.