Born in Campgaw, New Jersey on August 12, 1911, Wyatt grew up in New York City; her father was a Wall Street investment banker, and her mother wrote for such publications as Commonweal and Catholic World. After attending the Chapin School and studying at Barnard, she became an apprentice at the Berkshire Playhouse in Stockbridge, Massachusetts, this at a time when acting was not considered a suitable profession for well-brought-up young women. Indeed, when Wyatt got a job as an understudy in a Broadway show, her name was removed from the New York Social Registry.
Wyatt's early Broadway credits included Give Me Yesterday, The Fatal Alibi, and the original production of the George S. Kaufman-Edna Ferber play Dinner at Eight, in which she was a replacement in the role of Paula Jordan. Throughout the 1930s and '40s, she appeared in such plays as W. Somerset Maugham's For Services Rendered, Philip Barry's The Joyous Season, and Clifford Odets' Night Music. Her last Broadway role was that of Nina Denery in Lillian Hellman's The Autumn Garden (1951).
Among her film credits, Wyatt had major roles in Lost Horizon (1937), None but the Lonely Heart (1944), and Gentleman's Agreement (1947). On TV's Father Knows Best, she played opposite Robert Young, winning three Emmy Awards for her work. In later years, she appeared as Mr. Spock's mother in the original Star Trek series and in the film Star Trek IV: The Voyage Home. She also played Katherine Auschlander on St. Elsewhere and made guest appearances on many other TV series.
In 1935, Wyatt married Edgar Bethune Ward; their union lasted until his death in 2000. Wyatt is survived by the couple's two sons, Christopher and Michael; three grandchildren; and five great grandchildren.