A good Samaritan rescued a 5-year-old girl who was allegedly kidnapped and sexually assaulted by an elderly man her mother left her with in Queens on Tuesday, according to new court documents.

The eagled-eyed witness spotted the suspect, identified as 75-year-old Franz Villa, with the child inside 74th Street – Roosevelt Avenue station and leaped into action.

The straphanger recognized the pair from a city-wide alert about the missing girl, who was kidnapped after her mother allowed Villa to watch her daughter when she ran into him at a grocery store in Jackson Heights.

She followed the pair and then snatched the young girl away from the creep before screaming to nearby police for assistance, according to the criminal complaint against Villa.

The officers, hearing the good Samaritan’s cries for help, removed the child from Villa and promptly arrested him.

Villa was charged with predatory sexual assault against a child, criminal sexual act in the first degree, kidnapping in the second degree and endangering the welfare of a child.

He was arraigned Thursday and held on $275,000 bail.

The young girl told officers that Villa took her to his Upper East Side apartment where he allegedly sexually assaulted her, according to the criminal complaint.

The child’s mother, Kimberly Pijuan, 30, is also facing charges after letting the man she barely knew take her daughter.

The mom and daughter had been shopping at a Foodtown supermarket Tuesday morning when they ran into Villa.

The sicko offered to take the girl to Frank D. O’Connor Playground to which Pijuan agreed and asked that he bring her back to their home in 30 minutes, the complaint states.

But Villa never showed up with her daughter. Pijuan then went to the playground and other local spots to search for them but couldn’t find them anywhere.

She called 911 and reported her daughter missing at about 1 p.m., according to the document.

Pijuan had met the older man a few months prior. She has been charged with one count of child endangerment.

The hero New Yorker has not been publicly identified.