Nelly, 40, was arrested after a state trooper allegedly smelled marijuana when he stopped a coach bus that didn't have proper stickers displayed in its windows, police said.
"Nelly was one of several individuals that was on a tour bus that was stopped and searched while traveling through Tennessee," Nelly's attorney Scott Rosenblum said in a statement to ABC News.
Rosenblum said a small quantity of MDMA, a drug best known as ecstasy or Molly, was discovered during the search.
"We are extremely confident that when the facts come out, Nelly will not be associated with the contraband that was allegedly discovered,“ the statement said.
The Tennessee Highway Patrol said that troopers found "crystal-type rocks that tested positive for methamphetamine" as well as marijuana, drug paraphernalia and numerous handguns when they searched the vehicle.
Putnam County Sheriff's Office told ABC News that Nelly has since posted a $10,000 bail and has been released. He is expected in court June 19.