This paper discusses the successful fabrication of a novel triple-layered poly(lactic-co-glycolic acid) (PLGA)-based composite membrane using only a single step that combines the techniques of solvent casting and thermally induced phase separation/solvent leaching. The resulting graded membrane consists of a small pore size layer-1 containing 10wt% non-stoichiometric nanoapatite (NAp)+1–3wt% lauric acid (LA) for fibroblastic cell and bacterial inhibition, an intermediate layer-2 with 20–50wt% NAp+1wt% LA, and a large pore size layer-3 containing 30–100wt% NAp without LA to allow bone cell growth. The synergic effects of 10–30wt% NAp and 1wt% LA in the membrane demonstrated higher tensile strength (0.61MPa) and a more elastic behavior (16.1% elongation at break) in 3wt% LA added membrane compared with the pure PLGA (0.49MPa, 9.1%). The addition of LA resulted in a remarkable plasticizing effect on PLGA at 3wt% due to weak intermolecular interactions in PLGA. The pure and composite PLGA membranes had good cell viability toward human skin fibroblast, regardless of LA and NAp contents.