The development of enzymatic browning is one of the main problems in the preservation of fresh-cut and oxygen sensitive fruits such as avocados. This study employed packaging solution based on PLA/cellulose nanocrystal (CNC) films with strong oxygen and UV barrier properties to prevent browning in avocado and prolong its shelf life. Specifically, the effects of package material types (neat PLA vs PLA/CNC nanocomposite) and storage conditions (temperature and time) on discoloration (browning), in-package humidity level and gaseous compositions, microbial growth, as well as shelf life were assessed. Enzymatic browning was visually evaluated and total discoloration (E*) quantified as function of storage time and temperature to estimate the shelf life of the avocados using polynomial third degree regression equation. Nanocomposite package inhibited the browning of avocado when compared to neat PLA package due to the higher oxygen barrier of nanocomposite film, which effectively delayed oxidation of packaged avocados. Compared to neat PLA film, packaging with nanocomposite film significantly slowed down the avocados’ respiration and maintained a high humidity atmosphere inside the package, which delayed the enzymatic browning, irrespective of storage conditions. PLA/CNC nanocomposite package extended the shelf life of fresh-cut avocados by additional 54 h and 98 h compared to neat PLA package, when stored at 23°C and 4°C, respectively. PLA-based films prevent the microbial growth. These results clearly demonstrate the potential of PLA/CNC film to extend the shelf-life of oxygen-sensitive food products.