On advice from her half-sister's husband, she adopted the stage name Dina Merrill, borrowing from Charles E. Merrill, a famous stockbroker like her father. Merrill made her debut on the stage in the play The Mermaid Singing in 1945. During the late 1950s and 1960s, Merrill was believed to have intentionally been marketed as a replacement for Grace Kelly, and in 1959, she was proclaimed "Hollywood's new Grace Kelly". Merrill's film credits included Desk Set, A Nice Little Bank That Should Be Robbed, Don't Give Up the Ship, Operation Petticoat, The Sundowners, Butterfield 8, The Young Savages, The Courtship of Eddie's Father, I'll Take Sweden, The Greatest, A Wedding, Just Tell Me What You Want, Anna to the Infinite Power, Twisted, Caddyshack II, Fear, True Colors, The Player, Suture, and Shade. She also appeared in made-for-TV movies, such as Seven in Darkness, The Lonely Profession, Family Flight, and The Tenth Month. Merrill appeared in numerous television series in the 1960s, such as playing the villain "Calamity Jan" in two 1968 episodes of Batman alongside then-husband Cliff Robertson. She also made guest appearances on two Bonanza episodes as Susannah Clauson, The Alfred Hitchcock Hour episode "Bonfire", The Bold Ones, The Love Boat; Quincy, M.E.; Murder, She Wrote; Roseanne, and The Nanny, as Maxwell Sheffield's disapproving and distant British mother. In 1971, Merrill appeared as Laura Duff in The Men From Shiloh in the episode titled "The Agnus Killer". Her stage credits include the 1983 Broadway revival of the Rodgers and Hart musical On Your Toes, starring Russian prima ballerinaNatalia Makarova. In 1991, she appeared in the rotating cast of the off-Broadway staged reading of Wit & Wisdom. & Dick Sheridan in New York City In 1991, Merrill and her third husband, Ted Hartley, merged their company, Pavilion Communications, with RKO to form RKO Pictures, which owns the intellectual property of the RKO Radio Pictures movie studio. In the 1960s and 1970s, Merrill was a recurring guest on several network television game and panel shows including The Match Game, To Tell the Truth, What's My Line, and Hollywood Squares.
Merrill was married three times. In 1946, she wed Stanley M. Rumbough Jr., an heir to the Colgate-Palmolive toothpaste fortune and entrepreneur. They had three children, Nedenia Colgate Rumbough, David Post Rumbough, and Stanley Rumbough III before divorcing in 1966. Later that year, she wed future Oscar-winning actor Cliff Robertson, with whom she had a daughter, Heather Robertson. The couple divorced in 1986. In 1989, she married producer Ted Hartley. Two of Merrill's four children predeceased her. On May 22, 2017, Merrill died at her home in East Hampton, New York at age 93. She had been suffering from dementia with Lewy bodies.
