A novel maize variety designated PH179D and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing maize variety PH179D with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PH179D 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 PH179D or a locus conversion of PH179D with another maize variety.