Cellulose nanocrystals (CNCs) have gotten a lot of attention due to their biocompatible and biodegradable properties in addition to high elastic modulus, low density, and their origin from the most available natural resources. In our group, we have shown that it is feasible to disperse CNCs into biodegradable matrices while employing solvents. Concentration of 1 wt% of freeze-dried CNCs were added to 75/25 wt% poly (lactic acid), PLA, and poly (butylene adipate-co-terephthalate), PBAT blends, based on an amorphous and a semi-crystalline PLA (aPLA and scPLA) using solution casting (in dimethylformamide, DMF) followed by melt mixing (under internal mixer). The CNCs were either incorporated into the matrix, dispersed phase, or in both during the solution casting stage. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to examine the CNCs' dispersion and distribution in the neat polymers, as well as their localization in their respective blends. The localized CNCs in the matrix or both phases migrated to the interface of PLA and PBAT after melt mixing. Mechanical and thermal properties of PLA/PBAT/CNC blend nanocomposites with localized CNCs at the interface were investigated thoroughly. CNCs play the role of nucleating agents in the PLA/PBAT blends and improved the crystallization behavior of scPLA or PBAT in the blends of scPLA/PBAT and aPLA/PBAT, respectively, with increases in the crystallization temperature and the degree of crystallinity. Although Young’s modulus and yield strength decreased in the neat PLA/PBAT blends, interfacial localization of CNCs improved these properties (mostly in scPLA/PBAT) to values closer to the neat PLAs, accompanied by improved elongation at break from 3 % (scPLA) to 150 % (scPLA/PBAT/CNC) and impact strength from 20 J/m (scPLA) to 95 J/m (scPLA/PBAT/CNC). More trace of solvent in aPLA/PBAT/CNC and better affinity of CNCs with solvent compared to polymers resulted in less effectiveness of CNC localization