The 13-year-old girl was watching a movie with her mother on February 20 when a 23-year-old man sat down near her, putting his coat in between them.
He then reached under the coat and sexually assaulted her, police allege, only stopping when her mother realised something was wrong and confronted him.
He fled the Glen Waverley cinema but was later caught by police and charged with five counts of sexual assault.
He is due to appear at Melbourne Magistrates Court on April 29.