Nanochitosan, which was prepared by ionotropic gelation of chitosan and polyphosphate ions, had an average particle size of 112 nm. The nanochitosan was incorporated in formulations for chitosan-based nanocomposite (Ch-NCh) films and coatings. The 80% nanochitosan (v/v) containing film (Ch80NCh + Add) was the most compact and thinnest, followed by the 40% nanochitosan (v/v) containing film (Ch40NCh + Add) and the 1% chitosan-plus-additives film (Ch + Add) which was highly porous and the thickest. The capability of the coating formulations to extend the postharvest life of cv. Sinta papaya fruits, which were stored at 14.6 °C and 79% relative humidity, was evaluated. Control (uncoated) and blank (additives only, Add only) coated fruits reached the limit of marketability on the 7^th and 10^th days of storage, respectively. The Ch + Add coated fruits reached the limit of marketability on the 14^th day of storage. The Ch-NCh coated fruits did not reach the limit of marketability at the end of the 26-d storage period. The Ch-NCh coatings retarded peel color change, minimized disease incidence, shriveling and weight loss, and maintained pulp firmness. Titratable acidity of the Ch80NCh + Add coated fruits peaked later (19^th day) than that of the other fruit samples which peaked on the 14^th day of storage. Total soluble solids (TSS) content generally increased during storage with the Ch-NCh coated fruits generally having lower TSS readings. Results indicate that chitosan-based nanocomposite coatings retard fruit ripening in papaya cv. Sinta.