The 18-year-old heir secretly entered an unnamed facility in Utah in August shortly after he violated his probation order after testing positive for cannabis on July 30, 2012.
According to RadarOnline.com, he checked out of the treatment facility in November two months ahead of schedule.
A source close to the family said: "Conrad was scheduled to be in rehab until January, but he was released early on November 11, 2012, and returned home to spend time with his family for Thanksgiving."
Conrad's legal troubles began when he was involved in a car accident in November 2011 when he crashed his vehicle into two parked cars.
He had left the scene by the time cops arrived and later pictures emerged showing two unopened bottles of wine, a bottle of medical marijuana - which is legal in the state of California if prescribed - and some cigarette papers.
Conrad's parents are Rick and Kathy Hilton and as well as his most famous sister Paris his siblings also include daughter Nicky and brother Barron.