Sacks first got into acting after a bit part in an episode of The Love Boat when it was filming in the Pacific. His first role came about in the series The Restless Years in the late 1970s, which started him on the television circuit in Australia. He emigrated to Hollywood in the 1980s, guest starring in series such as thirtysomething, but preferred Australia, and so he returned there after a few years. Also had guest appearances in;Love in Limbo, Encounters, Irresistible Force, Fields of Fire III, All the Way, Touch the Sun: Princess Kate, Slate, Wyn & Me, Tricheuse, La, Emoh Ruo, Stock Squad and The City's Edge.
Against his first instinct, Sacks took the role of Detective P.J. Hasham in the 1994 series Blue Heelers. The show rocketed him to fame, most notably his 7-year "will-they-or-won't-they" relationship with Constable Maggie Doyle (Lisa McCune) which ended with her death in a seventh-season episode.
During the time he starred on the show, Sacks married Kate and had two children, Jack and Ned and had leading roles in two major Australian miniseries: Do or Die and My Husband My Killer (both 2001).
After playing P.J. for eleven years, and being one of only three original cast still on the show in the twelfth season, Sacks left Blue Heelers to spend time with his growing family. His last episode aired on August 10, 2005. Sacks expressly asked the producers not to kill his character, so that he could return for a guest spot in the future. He did not get the chance, however: the show was cancelled in early 2006.
Sacks is also a director, having directed episodes of Blue Heelers, and a short film called Crushed.