A biodegradable thermoplastic polymer made from renewable resources like sugarcane and maize starch, polylactic acid (PLA), is an environmentally beneficial substitute for plastics made from petroleum. PLA has drawbacks in mechanical strength, thermal stability, and moisture resistance despite its environmental benefits. Incorporating natural fibers and biomass has been the focus of recent research aimed at improving the characteristics of PLA, with fungal biomass emerging as a possible reinforcement. In addition to increasing PLA’s mechanical strength, elasticity, and toughness, fungal biomass also decreases water absorption and improves thermal stability. Fungal biomass is rich in polysaccharides like chitin and glucans. Several fabrication methods are investigated, such as injection molding, compression molding, manual layup, filament winding, and additive manufacturing. The results show that PLA-based biocomposites have potential for use in sustainable applications; however, more study is required to solve production issues and enhance material performance. PLA is biodegradable through a combination of chemical and microbiological processes; industrial composting degrades PLA more quickly than home composting. This analysis looks at how different fillers, like metal oxides, ceramics, and natural fibers, affect PLA’s functionality. Applications for PLA composites in 3D printing, construction, automotive, and medical fields are growing. To increase the applicability and effectiveness of PLA-based materials across a range of industries, future research should concentrate on strengthening mechanical qualities, enhancing filler compatibility, and evaluating long-term durability.