Peta Gia Wilson was born November 18, 1970, in New South Wales, Sydney, Australia. The daughter of Darcy Wilson, a retired warrant officer, and Karlene, a caterer, Peta and her family moved more than a dozen times before finally settling down in Papua New Guinea (where her father was stationed), where she was raised. A self-professed tomboy, Wilson was a champion basketball player in Australia and also an accomplished sailor, having been named Australian Champion Trailer Sailors along with her brother and father.

Educated at an all-girls Catholic School in Brisbane, Queensland, Australia, Wilson turned to athletics as a means to stay out of trouble, though her mother enrolled her into deportment classes in attempts to discourage the more tomboyish traits that accompanied Wilson's fondness for sports. It was during these courses that Wilson was spotted by a modeling agent who encouraged her to consider a career on the catwalk. Peta decided to take off to Europe and pursue a modeling career. She worked as a model for several years and suffered from an eating disorder; she soon grew tired of modeling and decided to try her hand at acting.

Studying at the Actors Circle Theater in L.A. under the tutelage of Arthur Mendoza, Wilson began to get small roles in such independent films as Loser (1996), and set her television career into motion with an appearance on the HBO series Strangers. Shortly before her departure for New York in 1996 to continue her studies in theater, Wilson's agent persuaded her to audition for the television series La Femme Nikita a happy coincidence that resulted in Wilson's casting as the title character in the USA series based on Luc Besson's Nikita (1990). Peta also made cameo appearances in 1997, in Raw is War. She has also appeared in the 1998 film One of Our Own and Mercy, 2 years later, directed by her then-boyfriend Damian Harris.

When not fighting crime on La Femme Nikita, Peta enjoys outdoor activities such as scuba diving, swimming, playing cricket, and gardening, and engages in alternative medicine like yoga and acupuncture. Peta also funds causes that are important to her; she is presently working on founding a Julliard for disadvantaged children, and is raising money with her company, Psycht, which sells sunglasses, running shoes, watches, and other accessories. Peta has also founded a production company called Sweet Lick Productions.