Merrill acted in twenty-two motion pictures, including Desk Set with Katharine Hepburn and Spencer Tracy, The Sundowners, Don't Give Up the Ship, Caddyshack II, I'll Take Sweden with Bob Hope, The Young Savages with Burt Lancaster, A Nice Little Bank That Should Be Robbed with Mickey Rooney, Catch Me If You Can, Operation Petticoat with Cary Grant (who had previously been married to her cousin, Woolworth heiress Barbara Hutton) and Tony Curtis, The Courtship of Eddie's Father with Glenn Ford and Ron Howard, Butterfield 8 with Elizabeth Taylor, A Wedding with Desi Arnaz, Jr. and Carol Burnett, True Colors with John Cusack and The Player with Whoopi Goldberg. Merrill appeared regularly on television in the 1960s. For example, she did a stint as one of the What's My Line? Mystery Guests on the popular Sunday Night CBS-TV program.

The actress has been married three times. Her first husband was Stanley M. Rumbough, Jr., an heir to the Colgate-Palmolive toothpaste fortune and entrep