In 1948, her family moved to Los Angeles, California, where she graduated in 1954 from Hollywood High School and began studying acting and appearing in school plays. She attended both Los Angeles City College and the University of California at Los Angeles.

Lee then got a break as a guest on two episodes of CBS's The George Burns and Gracie Allen Show. She soon found an agent, who landed her a job in an episode of The Roy Rogers Show, followed by a spot in 1953 on the series Adventures of Superman. That same year, while acting in a small theater production of On the Town, she landed a role as bride Ruth in the Academy Award-nominated musical Seven Brides for Seven Brothers, still billed as Ruta Kilmonis.

After that success, Lee appeared in several films including Anything Goes (1956), Funny Face (1957), Witness for the Prosecution (1957), and Marjorie Morningstar (1958). In 1962, Lee had the female lead in the Rat Pack comedy/Western film Sergeants 3 starring Frank Sinatra, Dean Martin, Sammy Davis Jr. and Peter Lawford. She then co-starred with Audie Murphy and Darren McGavin in a Western, Bullet for a Badman (1964).

In addition to films, Lee has appeared in dozens of guest-starring roles on television. For a number of years, she seemed to be everywhere on the screen. From 1957 to 1959, she was cast in different roles in eight episodes of the CBS crime drama series, The Lineup and also played the leading lady in three episodes of Maverick, "The Comstock Conspiracy" with James Garner and "The Plunder of Paradise," and "Betrayal" with Jack Kelly. In 1959 and 1960, she was cast in four episodes of John Bromfield's syndicated crime drama, U.S. Marshal.

She appeared as Ellen Barton in the 1960 episode "Grant of Land" of the ABC Western series, The Rebel, starring Nick Adams. She also made five guest appearances on the CBS courtroom drama series Perry Mason between 1958 and 1965, including murderer Connie Cooper in "The Case of the Screaming Woman" (1958), defendant Millie Crest in "The Case of the Foot-Loose Doll" (1959), also in 1959, she appeared as Vita Culver in “The Case of the Prudent Prosecutor”. Lee starred as Vivian Cosgrave in the episode "The Case of the Libelous Locket" (1963).

Lee was further cast on Richard Diamond, Private Detective, Alfred Hitchcock Presents, Maverick, Mickey Spillane's Mike Hammer, Sugarfoot, M Squad, Gunsmoke, 77 Sunset Strip, The Alaskans, Colt .45, Wagon Train, Hawaiian Eye, Rawhide, The Wild Wild West, Ironside, The Fugitive and three episodes of Hogan's Heroes. Lee appeared in two guest spots of The Andy Griffith Show in 1962 and 1965. In 1963, she was cast in CBS's The Twilight Zone in the episode "A Short Drink from a Certain Fountain", as a woman whose elderly husband undergoes a scientific experiment and then ages backward.

In 1963, Lee guest starred as Lucy Tolliver in the twelfth episode "Enough Rope" of the NBC/WB Western series, Temple Houston, with Jeffrey Hunter as an historical figure, the frontier Lawyer Temple Lea Houston, youngest son of Sam Houston. Temple Houston was canceled after twenty-six weeks. Of Hunter, Lee said, "He was one of the prettiest people that ever was put on the screen, God, he was gorgeous."

In 1964, Lee called then-Soviet Premier Nikita Khrushchev, asking him to pardon her grandmother Ludvise Kamandulis, who had been in an internment camp in Siberia since World War II. The pardon was granted, and Lee's grandmother came to live with her in California in 1964. Kamandulis died two years later. Lee again rescued a relative from the former Soviet Union when she secured custody of her 18-year-old cousin, Maryte Kaseta, from Lithuania in 1987.

Lee also began appearing regularly on game shows such as Hollywood Squares, You Don't Say and Match Game. In the early 1970s, Lee continued to perform in both films and television roles on Love, American Style, The Mod Squad, and a role in the film The Doomsday Machine (1972). By 1974, Lee had grown frustrated by an increasing lack of roles, and took a job co-hosting the daytime game show High Rollers. She remained with the show until 1976.

During the 1980s, she lent her voice to episodes of The Flintstone Comedy Show and The Smurfs, in addition to guest roles on CHiPs, Fantasy Island, The Love Boat and Charles in Charge. Lee also performed extensively in the mid-1980s on stage, including the title character in the musical Peter Pan.

From 1988 to 1989, Lee had a recurring role on the CBS sitcom, Coming of Age. In 1989, she played the role of Sally Powers in the television movie Sweet Bird of Youth with Elizabeth Taylor. In the 1990s, Lee continued to appear in episodic television, most notably on the sitcom Roseanne. Lee appeared as the girlfriend of Bev Harris (Estelle Parsons) whose character disclosed she was gay.

She played the wife of Comedian Jerry Lewis in the British comedy-drama Funny Bones (1995), in which they play the parents of the Oliver Platt's character. In 2002, Lee was presented one of the Golden Boot Awards for her work in western television and cinema.

In 2006, Lee received a star on the Hollywood Walk of Fame for her contributions to the television industry. In 1995, a Golden Palm Star on the Palm Springs Walk of Stars was dedicated to Lee.

In February 2008, Lee appeared as Clairee in a production of Steel Magnolias with Sally Struthers at the Casa Mañana theatre in Fort Worth, Texas. In October 2010, Lee played the role of Miss Mona in The Best Little Whorehouse in Texas, also at the Casa Mañana Theatre.

Lee has been involved with the charitable organization "The Thalians" for over fifty years. In addition to raising money and providing services for troubled youth and mental health organizations, Lee, who is also the board chairman, has co-produced the annual Ball of the Thalians with Debbie Reynolds throughout those five decades. In 2011, she stepped down after 55 years of involvement with the Thalians, and is now an emeritus member.

In 1976, Lee married Texas restaurant executive Webster B. "Webb" Lowe, Jr. They divide their time between their homes in Hollywood, Palm Springs, Fort Worth and Mexico. She has no children. Lee describes her political views as "conservative" and she appeared at the 1972 Republican National Convention. On August 24, 2013, Lee was inducted into the National Lithuanian American Hall of Fame.