Production of wheat germ oil nanoemulsions (WGO), having 114.7 nm average zeta size, 0.144 PD index, 14.76 mV zeta potential value, were successfully carried out. TBARS, FFA, PV, CD, and CT tests, lipid nutritional quality indexes (AI, HH, PI, TI, EPA/DHA, PUFA/SFA, and n3/n6), color measurements, and the changes in sensory quality were studied in cooked mackerel fillets stored at 4 degrees C for 11 days. WGO nanoemulsion has delayed the increase in TBARS, FFA, PV, CD, and CT values of cooked fish fillets by 36.1%, 20.5%, 32.2%, 37.7%, and 68.4%, respectively. The changes in lipid nutritional quality indexes, b* value and sensory quality of cooked fish fillets treated with WGO nanoemulsions were found to be more stable. The oil quality of the cooked fish fillets treated with WGO nanoemulsions was successfully protected because of WGO loaded nanoemulsions provided a larger contact area on the surface of the fish fillets.