A sicko followed a young woman into a Bronx apartment building and brutally raped her, cops said today.

The creep stalked the 21-year-old woman as she walked on East 143rd Street in Mott Haven around 1:30 a.m. Sunday, cops said.

He forced the woman into a stairwell, where he raped her.

The suspect is described by cops as a black man in his 20s, about 5’7” tall and has a bump on his left cheek.

He was wearing black sweatpants, a black hooded sweatshirt and a Yankees cap.