Knight has a history of legal problems
US rap music mogul Marion "Suge" Knight has been arrested on assault and drug charges after being accused of assaulting his girlfriend.
Police in Las Vegas said the 43-year-old was found "violently beating" an unnamed woman while holding a knife when officers arrived on the scene.
The woman was not stabbed but was treated at a hospital for injuries.
Knight is expected to be released on bail shortly, and is scheduled to appear in court on 26 September.
Police did not release the woman's name or age, but said she identified herself as Knight's girlfriend of three years.
Officers discovered the founder of Death Row Records attacking his partner in a car park after being arriving at the scene of a minor traffic accident.
Knight was also found to be in possession of ecstasy and the prescription narcotic Hydrocodone, police said.
Lawyers representing Knight said they wanted to gather information about the arrest before commenting.
Knight has a history of legal problems including time in prison for drug offences and breaking parole.
Death Row Records released several seminal gangster rap albums by the likes of Tupac Shakur, Dr Dre and Snoop Dogg.
In 2006, a judge ordered trustees to take over the company after Knight filed for bankruptcy.