A Los Angeles County Superior Court Judge Robert Perry ordered the release of Johannes Mehserle, convicted of a fatal shooting of a man during a platform scuffle.
Perry determined that with time served and good conduct, Mehserle should be released Monday.
Mehserle was convicted in July 2010 and sentenced in November 2010 to two years in prison for involuntary manslaughter of Oscar Grant.
Mehserle and his partner were responding to an unruly crowd on a BART platform in Oakland on New Year's Day 2009.
While attempting to subdue Grant, who was unarmed, Mehserle fatally shot Grant in the chest. Mehserle said he was intending to use his Taser, not his firearm.
The case, which inflamed racial tensions in the Bay Area and sparked violent protests, was moved prosecuted in Los Angeles due to pre-trial publicity.
Grant's supporters said they plan to rally in front of the U.S. attorney's offices in Oakland and Los Angeles when Mehserle is released early Monday morning.