Biopolymers are environmentally friendly materials obtained from natural sources that can be chemically or biologically synthesized. Polymers biosynthesized by microorganisms like polyhydroxyalkanoates (PHA) have outstanding biodegradability-related properties; nevertheless, it compromises their processing competence and, hence, their quality. Despite PHA processing generating high production costs, it is possible to achieve superior optical, mechanical, thermal, and surface features by combining PHA and reinforcements or fillers that are also compatible with a sustainable purpose, reducing costs, increasing durability, and facilitating manufacturing and transportation; these materials are called green composites. PHA-based green composites are relatively recent advanced materials that can be generated from renewable sources in fibers, laminates, and particulates form (agro-industrial waste, wood fibers, etc.), becoming a promising alternative to petroleum-based plastics replacement meeting international market requirements.