Reed won the Academy Award for Best Supporting Actress for Fred Zinnemann's war drama film From Here to Eternity (1953).

Later in her career, Reed replaced Barbara Bel Geddes as Miss Ellie Ewing Farlow in the 1984–1985 season of the television melodrama Dallas; she successfully sued the production company for breach of contract when she was abruptly fired upon Bel Geddes' decision to return to the show.

[2] She had two brothers, William Lee (1927–1993), and Keith Mullenger, and two sisters, Lavone “Heidi” Flynn (1924–2019) and Karen Moreland (born 1942).

[3][4] In 1936, while she was a sophomore at Denison (Iowa) High School, her chemistry teacher gave her the book How to Win Friends and Influence People.

After receiving several offers to screen test for studios, Reed eventually signed with Metro-Goldwyn-Mayer; however, she insisted on finishing her education first.

[7] In 1941, after signing with Metro-Goldwyn-Mayer, Reed made her film debut in The Get-Away opposite Robert Sterling; she was then billed as Donna Adams.

Reed starred in Calling Dr. Gillespie (1942) and Apache Trail (1942), then did a thriller with Edward Arnold, Eyes in the Night (1942), directed by Fred Zinnemann.

[11] Reed collaborated with her Denison High school chemistry teacher Edward R. Tompkins (who worked on the Manhattan Project) on the 1947 MGM film The Beginning or the End, which dealt with the history and concerns of the atom bomb.

[12] Reed was top billed in a romantic comedy Faithful in My Fashion (1946) with Tom Drake, which lost money.

MGM lent Reed to RKO for the role of Mary Bailey in Frank Capra's It's a Wonderful Life.

"[9] Back at MGM, she appeared in Green Dolphin Street (1947) with Lana Turner and Van Heflin, a financial hit.

Paramount borrowed Reed for two films with Alan Ladd, Beyond Glory (1948), where she replaced Joan Caulfield at the last minute,[14] and Chicago Deadline (1949).

Reed was the love interest of Randolph Scott in Hangman's Knot (1952), then was borrowed by Warner Bros for Trouble Along the Way (1953) with Wayne.

Reed played the role of Alma "Lorene" Burke, girlfriend of Montgomery Clift's character, in the World War II drama From Here to Eternity (1953).

[18] The qualities of her parts did not seem to improve: she was the love interest in The Caddy (1953) with Martin and Lewis at Paramount; Gun Fury (1953) with Rock Hudson; Three Hours to Kill (1954) with Dana Andrews; and They Rode West (1954) with Robert Francis.

[19] She continued to appear in features, usually as the love interest, in The Far Horizons (1955) at Pine-Thomas Productions with Fred MacMurray and Charlton Heston as Lewis and Clark, playing Native American Sacagawea; The Benny Goodman Story (1956) with Steve Allen at Universal, playing Goodman's wife; Ransom!

In the show, Reed's character, Donna Stone, is a loving mother and wife, but also a strong, smart woman with feelings and a sense of humor.

"[25] In a 2008 interview, Paul Petersen, who portrayed her son Jeff Stone in the series, also shared his opinions about the production's significance: That's what the show was really about, the importance of family.

[27] She returned to acting in the late '70s, appearing in the TV movies The Best Place to Be (1979) and Deadly Lessons (1983) and a guest stint on The Love Boat.

[28] In the 1984–85 season of the TV series Dallas, Reed replaced Barbara Bel Geddes, who left the show due to illness, as Miss Ellie Ewing.

[25]After Bel Geddes recovered and unexpectedly expressed a desire to return to the role for the 1985–86 season, Reed was abruptly fired.

[32] Reed, who was a registered Republican, became interested in politics in particular during the Vietnam War when she became concerned that her adopted son, Tony, might be drafted.

"[33][34] In a 1971 interview with the Los Angeles Times, Reed said, In the beginning, we felt [Tony] should serve his country in a noncombatant role.

[43] In May 2010, Turner Classic Movies honored Reed as their star of the month[44] which saw Mary Owen pay a special tribute to her mother.