The effect of postharvest dipping treatments with 0.5 mM melatonin (MT) and 1% chitosan (CT) either alone or in combination on quality of pre-climacteric ‘Williams’ bananas during ripening at ambient conditions were investigated. MT or CT treatments delayed ripening by retaining greener peel, higher firmness, titratable acidity (TA), but lower total soluble solids (TSS) and TSS/TA, weight loss, browning and electrolyte leakage than the control. Total phenol (TPC) and flavonoid contents (TFC) in both peel and pulp increased up to 6 days and then decreased and was higher in treated fruit than the control. Vitamin C content decreased up to 3 days, then increased and was higher in treated fruit than control. MT and CT combination exhibited the highest TPC, TFC and vitamin C contents compared to other treatments. Radical scavenging capacity (RSC) of peel and pulp increased up to 6 days, then decreased and was higher in treated fruit than the control. The treated fruit exhibited lower polyphenoloxidase (PPO) and hydrolytic enzymes but higher peroxidase (POD) activities in both peel and pulp than the control. Postharvest treatments with 0.5 mM MT and 1% CT alone or in combination could be used to retain quality of ‘Williams’ bananas during ripening.