The Grammy-winning singer entered the plea during a brief court hearing on Friday. He also entered a special plea in which he maintained his innocence in the case.
Superior Court Judge Mark Young sentenced the 39-year-old singer to three years of formal probation. Young said Green, whose real name is Thomas DeCarlo Callaway, will be allowed to travel for work.
Green entered the plea just before a preliminary hearing, which would have disclosed potential evidence against him, was scheduled to begin.
Prosecutors rejected a rape charge against Green when he was charged with the felony drug charge in October 2013. His attorney Blair Berk has said Green had consensual sex with the woman he gave ecstasy to during the 2012 dinner.