Cops have arrested a 31-year-old homeless guy they say broke into a sleeping 15-year-old girl’s Bronx bedroom and tried to sexually assault her, officials said on Saturday.

Marlon Alvarez was charged with attempted rape, burglary, sex abuse & forcible touching for the May 30 attack inside the Vyse Ave. apartment in Crotona.

Alvarez broke through the girl’s bedroom window around 4:30 a.m. & got on top of her as she slept, cops said.

Just as Alvarez was about to pull her dress off, she woke up and screamed, alerting her mom. The mother chased Alvarez out of the home & called the police.

Police identified Alvarez as the would-be rapist early in their investigation, but he disappeared, officials said.

Alvarez was spotted Friday morning on Bruckner Blvd. in Mott Haven & taken into custody, cops said.