The incident happened around 4:30 a.m. Chris Hollosy, believed to be the singer's bodyguard, was also arrested on felony charges.
According to a police report, Brown was taking a picture with a fan when 20-year-old Isaac Parker attempted to join in. That's when Brown reportedly said, "I'm not into that gay [expletive]. I feel like boxing."
Brown then allegedly punched Parker in the face. The report states that the singer's body guard stepped in and also punched Parker in the face. Neither Brown's publicist nor his attorney has commented on the arrest.
Parker was treated at the hospital and released. The extent of the Parker's injuries prompted police to arrest Brown and Hollosy.
Brown is expected to be arraigned in a Washington D.C. court Monday afternoon.
The 24-year-old R&B singer remains on probation in Los Angeles for the 2009 beating of his then-girlfriend pop star Rihanna before the Grammy Awards. He received five years probation, but earlier this year prosecutors said he had not properly performed his court-ordered community service.
Brown's probation was briefly revoked earlier this year after a hit-and-run accident. It was reinstated after he agreed to perform another 1,000 hours of community service.
The singer has been involved in a number of high-profile altercations, including a nightclub brawl between his entourage and that of rap star Drake.
The Grammy Award winner's arrest in Washington could prompt prosecutors in L.A. to try and revoke his probation and ask a judge to impose additional penalties.
Brown is expected to appear in court on Monday. He is also scheduled to be back in court in L.A. next month to update a judge on his probation.