The 38-year-old, whose real name is Thomas DeCarlo Calloway, pleaded not guilty. Prosecutors declined to file sexual assault charges against Green, citing a lack of evidence.
Dressed in a relatively subdued all-black ensemble, Green, the Grammy-winning singer of the hit "Forget You" and half of the duo Gnarls Barkley, appeared before an L.A. County Superior Court judge Monday afternoon. He was accompanied by his attorney, Blair Berk, who entered his plea and waived his right to a speedy trial.
Green is alleged to have put ecstasy in the 33-year-old woman's drink as they dined together at a Wokcano restaurant in July 2012. The woman told authorities she later woke up naked in bed with the singer in her hotel room.
Berk said her client had "consensual relations" with the woman, and called the claims of sexual assault "false and unfounded."
"We are pleased that the Los Angeles County district attorney has completed its investigation," she said Monday.
If found guilty of furnishing a controlled substance, a felony, Green could face up to four years in prison.
"The Voice," which won the Emmy for best reality-competition series, is NBC's highest-rated entertainment program and one of the top shows on television, drawing 13.8 million viewers last week. It has also proved to be a valuable lead-in for other series, like the network's freshman hit, "The Blacklist."
NBC representatives were not immediately available for comment on the case.