Lansing was born Joy Rae Brown at Holy Cross Hospital, Salt Lake City, Utah in 1929 to Jack Glen Brown (also known as Glen Jack Brown and Glenn Jack Brown; 1900–1960), a shoe salesman and orchestra musician, and Virginia Grace (née Shupe) Brown, a housewife (1908–1984).

She would later be known by her stepfathers' Surnames, i.e. Wassmansdorff and Loveland. In 1940, her family moved to Los Angeles, where her half-brother, Larry Vernon Loveland, was born the same year. She began modeling in her teens, and at age 14 was signed to a contract at MGM. She completed high school on the studio lot.

Lansing's film career began in 1948, and in 1952, she played an uncredited role in MGM's Singin' in the Rain. She received top billing in Hot Cars (1956), a crime drama involving a stolen-car racket. In the opening sequence of Orson Welles's Touch of Evil (1958), she appeared as Zita, the Dancer who dies at the end of the famous first tracking shot, during which her character exclaims to a border guard, "I keep hearing this ticking noise inside my head!"

What was possibly Lansing's best role may ironically have been her least-seen as the leading lady in The Fountain of Youth, a Peabody Award-winning unsold television pilot directed by Orson Welles for Desilu in 1956 and broadcast on the Colgate Theatre two years later. The half-hour film remains available for public viewing at the Paley Center for Media in New York City and Los Angeles.

In 1957, she played Vera Payson in the Perry Mason episode, "The Case of the Crimson Kiss". She is best known perhaps as Shirley Swanson in The Bob Cummings Show or Love That Bob (1956–59). She appeared in several episodes as a busty model who was the foil for Photographer Bob Collins, Cummings' series name. The series ran for 173 episodes. She achieved some distinction for beating out Lois Lane (Noel Neill) to marry Superman (George Reeves) as the title character in "Superman's Wife", a 1958 episode of The Adventures of Superman.

She had a brief role as an astronaut's girlfriend in the 1958 sci-fi classic Queen of Outer Space. She had fourth billing in another sci-fi story, 1959's The Atomic Submarine. During the 1960s, she starred in short musical films for the Scopitone video-jukebox system. Her songs included "The Web of Love" and "The Silencer".

In the 1960–61 season of Klondike, Lansing appeared as Goldie with Ralph Taeger, James Coburn, and Mari Blanchard. In 1960, she appeared as Evelyn in the "Election Bet" episode of the Mr. Lucky TV series (season 1, episode 34). In May 1963, Lansing appeared in Falcon Frolics '63. The broadcast honored the men stationed at the Vandenberg Air Force Base. By 1956, she had appeared in more than 200 television shows. The real count according to IMDb is around 104 appearances.

In 1964, Producer Stanley Todd discussed a film project with Lansing, tentatively titled Project 22, with location shooting planned in Yugoslavia, and George Hamilton and Geraldine Chaplin named to the cast. The movie was never made.

Lansing played "Lola" in the romantic comedy Marriage on the Rocks (1965) with a cast that included Frank Sinatra, Deborah Kerr, and Dean Martin. She previously had appeared in Sinatra's drama A Hole in the Head and in Martin's comedy Who Was That Lady?. She turned down the chance to replace Jayne Mansfield in The Ice House (a horror film), and instead appeared opposite Basil Rathbone (in his last film appearance) and John Carradine in Hillbillys in a Haunted House, as Mamie Van Doren's replacement. Her last film was Bigfoot (1970).

Lansing died from breast cancer on August 7, 1972, at St. John's Hospital, Santa Monica, California. She had been treated surgically for the disease two years earlier. She also suffered from severe anemia. She was survived by her mother, half-brother, and paternal grandmother. While some press accounts gave her age as 37, she was actually 43 years old.