Connell is the only son of Evan S. Connell, Sr. (1890-1974), a physician, and his wife, Ruth Elton Connell. He has a sister, Barbara (Mrs. Matthew Zimmermann, to whom he dedicated his novel Mrs. Bridge). He graduated from Southwest High School in Kansas City in 1941 and attended Dartmouth College but graduated from the University of Kansas in 1947, with a B.A. in English. He also studied creative writing at Columbia University in New York and Stanford University in California.

Connell lives in New Mexico. In 2009, he was nominated for the third Man Booker International Prize.

Connell's novels Mrs. Bridge (1959) and Mr. Bridge (1969) are bittersweet, gently satirical portraits of a conventional, unimaginative upper middle class couple living in Kansas City from the 1920s to the 1940s. The couple tries to live up to societal expectations and to be good parents, but are sadly incapable of bridging the emotional distance between themselves and their children, and between each other. The pair of novels was made into a 1990 Merchant-Ivory motion picture, Mr. and Mrs. Bridge, starring Paul Newman and Joanne Woodward, the production was not highly successful. Hal Hinson wrote in The Washington Post that "the film comes with a built-in problem. Its subject is emotional repression, and the challenge is to make a film about a soul-deep conservatism that doesn't itself suffer from the excess caution and lack of dynamism that its characters do. However, it's not a challenge that is met."

Connell's 1960 novel, The Patriot, is the story of Melvin Isaacs, aged 17, and his experiences in naval aviation school during the Second World War. Melvin faces the terrifying reality of training, which is in itself a highly dangerous activity, and with the likelihood of his "washing out" (failing). Melvin's attempts to communicate the realities of his experience to his father are rebuffed. The characters of Melvin and his father Jacob are similar in many respects to those of Douglas and Mr. Bridge.

Connell's 1984 biography of Custer, Son of the Morning Star, won critical acclaim, was a bestseller, and was made into a television miniseries in 1991.

Dorothy Parker described Connell as "a writer of fine style and amazing variety".[1]