A novel maize variety designated PHJ8C and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing maize variety PHJ8C with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PHJ8C through backcross conversion and/or transformation, and to the maize seed, plant and plant part produced thereby. Hybrid maize seed, plant or plant part produced by crossing the variety PHJ8C or a trait conversion of PHJ8C with another maize variety. Inbred maize varieties derived from maize variety PHJ8C, methods for producing other inbred maize varieties derived from maize variety PHJ8C and the inbred maize varieties and their parts derived by the use of those methods.