Ex-boxing champ Victor Ortiz plead not guilty to 3 felony sexual assault charges -- including forcible rape -- in front of a judge on Wednesday ... and then smiled on his way out of court.
Ortiz -- a 31-year old former WBC welterweight champ -- was charged with forcible rape, forcible oral copulation and forcible digital penetration for an alleged incident that went down in an Oxnard, CA home on March 19.
V.O. was arrested and charged in September ... before being bailed outta county jail.
Ortiz finally faced a judge this morning in Ventura County .