"Naked and Afraid" star Brandon Pope won't be naked -- he has a new jumpsuit -- but he has reason to be afraid ... after cops nabbed him for allegedly spying on a bathing family member.

Law enforcement sources tell TMZ ... Pope was busted in Arkansas after he was accused of spying on a teenage family member who was taking a bath in his house.

We're told someone inside the house called cops, and Pope was ultimately arrested earlier this month on 1 felony count of voyeurism.