Police arrested Nelly in the early morning and took him to a jail in Des Moines, Washington, according to a report from the police department in nearby Auburn.
The report says a woman called 911 at 3:48 a.m. Saturday to report the alleged assault, which she says occurred on Nelly’s tour bus.
Police said Nelly, 42, had performed at the White River Amphitheater in King County just hours before the phone call was made.
Nelly tweeted Saturday afternoon that he is “Completely innocent” and confident he will be vindicated.
Nelly’s attorney, Scott Rosenblum, said the “Allegation is devoid of credibility and is motivated by greed and vindictiveness.”
Nelly was once one of the reigning kings of hip-hop.
In 2015, Nelly pleaded guilty to a misdemeanor possession of marijuana and drug paraphernalia, according to E! News..