Julian Dana William McMahon was born in Sydney, Australia, as the second of three children to Lady Sonia McMahon (née Sonia Rachel Hopkins) and Sir Billy McMahon, a government minister who served for over 21 years and later became Prime Minister of Australia from March 1971 to December 1972. Sir Billy passed away on March 31, 1988, at the age of 80, just four months before Julian's 20th birthday, and Julian's mother, Lady Sonia McMahon, died of cancer on April 2, 2010, at the age of 77, surrounded by Julian and his two sisters.
Julian is of Irish and English descent and began his educational journey at the University of Wollongong, where he started a Bachelor of Arts degree. However, he soon became bored and switched to a career in modeling, working primarily in commercials. In 1987, he began print modeling assignments in Los Angeles, New York, Milan, Rome, and Paris, and his appearance in a TV commercial promoting jeans in his home country made him popular enough to be cast as the lead in The Power, the Passion, an Australian "Dynasty"-like series.
After 18 months on The Power, The Passion, Julian joined the cast of Home and Away, another successful Australian series, where he won a best actor award from a national magazine. He later performed on stage, appearing in a musical version of Home and Away in Britain as well as in Love Letters in Sydney and Melbourne. In 1993, he starred in the feature film Wet and Wild Summer! with Elliott Gould, which led him to move to Hollywood to read for more American projects.
In 1992, Julian was cast as Ian Rain on NBC's daytime drama Another World, a role he played for two years before leaving to expand his range and experience. He appeared in several Los Angeles stage productions and also starred in the feature film Magenta in 1997. He then landed the role of Agent John Grant on Profiler for four seasons.
In his free time, Julian enjoys surfing, biking, and cooking. He is a fan of baseball, American football, and basketball, and he collects classic books.