The singer, who reached a plea deal with prosecutors in June in an effort to avoid jail, was in court on Tuesday for sentencing in relation to his attack on the "Umbrella" singer.
Los Angeles County Superior Court judge Patricia Schnegg also ordered Brown to take a year-long domestic violence prevention class. He also faces six months of hard community labor in his native Virginia.
Brown was arrested in February for beating and threatening Rihanna during an argument following a pre-Grammy Awards party.
Both stars pulled out of their planned performances at the awards show immediately after the incident.
The sentencing will also cost Brown almost $6,000 -- $5,000 in restitution and probation expenses. He must also pay a small criminal conviction fee and $400 to a domestic violence fund.
Outside court, Rihanna's lawyer Donald Etra said there were "no surprises" in the sentencing.
Speaking of his client, Etra said, "She was advised of what the plea agreement would be and she did not object that... The court just imposed the sentence envisaged by the plea agreement.
"She's doing fine and she's pursuing her career... She's tremendously appreciative of the support her family, her friends and her fans have given her throughout the world."
(c) 2009 WORLD ENTERTAINMENT NEWS NETWORK LTD. All global rights reserved. No unauthorized copying or re-distributing permitted.