A stalker followed a 48-year-old woman on a subway train, then chased her into a building during a harrowing encounter in Brooklyn, police said Friday.

Armed with surveillance images, cops are hoping to identify the stalker wanted for the chilling March 19 encounter, part of which was captured on video.

The victim told police that she was waiting for a Queens-bound J train at the Cypress Hills subway station about 6:30 a.m. when a man in a blue jacket, the lower half of his face covered, approached her.

“Hey, you cute,” the man, who is believed to be between 20 and 25-years-old said, leaving the woman uneasy.

When the train arrived, the man, who was carrying a shopping bag, followed her and sat across from her in the subway car, staring at her.

The woman got off at the Jamaica-Parson’s/Archer station in Queens — the train’s last stop — and the man followed her.

As she walked away from the station, the man continued to trail her.

As the panicked woman began to run, the stranger ran after her and chased her into a nearby building before wandering off.

The woman wasn’t injured, but was left rattled.

Police said the stalker is about 5-foot-5, 140 pounds with black hair. Besides the blue jacket, he was wearing a blue T-shirt, blue sweatpants, and light-colored sneakers, cops said.

Anyone with information regarding his whereabout is urged to call NYPD Crime Stoppers at (800) 577-TIPS. All calls will be kept confidential.