The 21-year-old 'Heart Attack' hitmaker, who reportedly split with Valderrama in 2012, was seen spending time with the actor at Knott's Berry Farm Halloween Haunt in Buena Park, Calif, reported E! Online.
Lovato, 21, and Valderrama, 33, split last year due to their age difference. In August, Demi joined Valderrama at Disneyland.