The primary objective of the study was to conduct mechanical, dynamic, thermal, and rheological analyses of composites based on PLA/PHBV blends. Specifically, three composites were produced with microcrystalline cellulose content at 5, 10, and 15wt.%. These materials were also subjected to aging tests. The findings of the study reveal the strengthening effect of microcrystalline cellulose and its positive impact on resistance to environmental factors. However, it is important to note that an excessive amount of filler decrease strength properties and processing issues. Despite this limitation, the study demonstrates the significant potential for using microcellulose and biodegradable PLA/PHBV blends to create high-strength, environmentally friendly polymer composites.