'16 and Pregnant' Valerie Fairman -- Arrested For Prostitution

Valerie Fairman -- one of the stars of MTV's "16 and Pregnant" -- was arrested for prostitution after cops say they spotted her streetwalking ... TMZ has learned.

21-year-old Fairman -- who appeared on season 2 of the show -- was allegedly walking the streets in New Castle, Delaware. We're told cops conducted the sting after getting a slew of citizen complaints about prostitution in the area. Valerie allegedly agreed to perform a sexual act for cash.

Valerie was arrested along with 7 other women.

Valerie became popular on "16 and Pregnant" after getting in multiple fights with her baby daddy over their daughter, Nevaeh.

We're told Valerie's still in custody.