On October 13, 1962, the world said aloha to Big (nee Palzis) who was born in Honolulu, Hawaii. Preston's biological father drowned when she was only three years old and her mother, a mental health administrator, married Peter Palzis (and eventually divorced in 1976). The future model/actress majored in drama at the University of Southern California when she was growing up.

At the age of 16, a fashion photographer discovered Preston and helped her get gigs in commercials and an audition for The Blue Lagoon. Although she lost the role of Emmeline to Brooke Shields Preston received attention for her comedic roles in films such as Mischief and Secret Admirer, both released in 1985. Preston first entered the scene with her role as a general's daughter on the 1983 television drama For Love and Honor.

In 1988, she was offered the role of Marnie Mason in the comedy Twins, opposite Danny DeVito and Arnold Schwarzenegger Although this seemed like a big break for her as an actress, the script didn't offer a specific character description and the role was not the one to boost Preston's acting career. This didn't stop her from winning more roles, such as Arthur Miller's The American Clock, a 1993 made-for-tv-movie in which her incredible acting talents were hard to miss.

As for romance, Preston's love life didn't include many long-term relationships, except for her present (and permanent) role as John Travolta's wife for the past nine years. Preston met her first husband Kevin Gage at age 23, when they were both cast in the film Space Camp. After being Mrs. Gage for almost three years, Preston moved in with actor George Clooney They lived together with their pet pig for a year until Clooney reunited with a former girlfriend. It is unknown who kept the pig. Preston moved in with Charlie Sheen whom she was briefly engaged to. She was accidentally shot in the leg in their apartment. Her luck began to change when she met Travolta in 1987 while they were filming The Experts in Toronto. They ran into each other again in Vancouver three years later when she was filming Run and Travolta was working on Look Who's Talking Too. They were married on September 5, 1991, in Paris by a French Scientology minister, but they had to renew their vows a week later in Daytona Beach, Florida, since their marriage in France was not considered legal. Their first son, Jett, was born April 13, 1992. In 1996, Preston was cast in the Cameron Crowe hit Jerry Maguire as Tom Cruise's sex obsessed icy girlfriend. After that, the roles began pouring in for Preston as she was cast in Addicted to Love, Nothing to Lose, Holy Man, Jack Frost, and Bar Hopping. She was last seen in the baseball romance For Love of the Game, co-starring Kevin Costner Preston's next role will be in this summer's sci-fi movie Battlefield Earth based on the novel written by Scientology founder L. Ron Hubbard. Preston and her husband are both high profile Scientologists. They recently celebrated the birth of their second child on April 3, 2000, a baby girl named Ella Bleu.