Eric Wells, 43, of Memphis was identified by the witness and later arrested. The car he was driving, the gold Honda Accord, was found in the 600 block of Woodstone Circle in Whitehaven.
Wells was charged with aggravated kidnapping, but he has not divulged the location of Webster, police said.
Police have not said how Wells and Webster know each other.
Webster was last seen wearing blue jeans and a black tank top with thin shoulder straps and white tennis shoes with rhinestones. She has a pink tongue ring and tattoo of a star or stars on the top of her foot.
Memphis police issued a CityWatch alert for Webster whose last address was listed in Lewisburg, Tenn. Anyone with information is asked to call 901-545-2677.