Brown was released from Men's Central Jail at 12:01 a.m., said Los Angeles County Sheriff's Deputy Tony Moore.
Brown, 25, had admitted last month in a Los Angeles court to violating his probation in Washington, D.C., where he allegedly punched and broke the nose of a man who jumped into a photo of the singer with two fans.
The singer has pleaded not guilty to misdemeanor assault and must still resolve that case.
Brown has been locked up since March 14 after he was kicked out of court-ordered rehabilitation in California for violating rules.
He had earned 234 days of credited jail time at the time of sentencing for days already spent in jail and court-ordered rehab. He was scheduled to be released by early July at the latest if required to serve out his entire sentence.
Inmates are released at the discretion of the county sheriff in a state-wide effort to reduce prison population.
The "Turn Up the Music" singer must also undergo therapy and random drug testing as part of his sentence from Los Angeles Superior Court Judge James Brandlin, who said he took into account an undiagnosed mental illness and the singer's young age when he assaulted Rihanna on the eve of the 2009 Grammy Awards.
Brown, who still must complete community service, made his mark in the music world as a teenager and, despite several brushes with the law, has been able to bounce back professionally after beating up his world-famous girlfriend.