Plastic pollution is a serious global environmental problem.  Plastic pollution can alter habitats and natural processes, reducing ecosystems’ ability to adapt to climate change, directly affecting millions of people’s livelihoods, food production capabilities and social well-being. Given the hundreds of million tons of plastic waste accumulating and the still escalating pace of plastic production, re-utilization of plastic residues is a necessary path to alleviate the gravity of the plastic pollution problem. To-date, only mechanical recycling is being applied at a large scale. Several factors, such as the low number of plastic types prone to be mechanically recycled, and the low quality of the secondary products severely restrict the potential of this solution to the problem of plastic waste. The OECD report (22/02/2022) estimated that world is producing twice as much plastic waste as two decades ago, with the bulk of it ending up in landfill, incinerated or leaking into the environment, and only 9-11% successfully recycled. Bio-recycling of plastic waste by microbial enzymes became in the last decades an emerging technology for plastic waste. Biodegradation processes started using enzymes from microbes (bacteria or fungi) to break down plastic waste into its basic components for reuse in the production of new plastic products or fuel. Microorganisms have developed enormously diverse metabolic pathways in the course of their evolution and some bacteria or fungi possess great variety of enzymes that can break down the molecular chains of recalcitrant plastics. In 2016, scientists discovered the bacterium Ideonella sakaiensis 201-F6 in a recycling yard for PET bottles in Japan. The bacterium was able to grow on PET and feed on it. The key enzyme is a hydrolase that has been named PETase, that breaks down PET into so-called MHET and the bacterium also has an enzyme for its degradation, MHETase.  Enzymatic biodegradation was expanded for a great range of polymers and with successful products for certain types of plastic waste. Numerous methods allowed researchers to obtain bio-materials with good technical substitution potential, novel properties and biodegradability. From this perspective, post-consumer plastic can be upcycled rather than only recycled. Biological degradation methods have the advantage that they can be applied to contaminated plastic waste (i.e., food or soil) and do not require previous separation of the different fractions. Furthermore, the high selectivity of enzymes could allow for a stepwise removal of specific components of the mixed-plastic waste, facilitating the downstream processing; that can go beyond the limits of mechanical and chemical recycling. Natural and engineered enzymes for plastic depolymerization have been extensively studied and their results published in  a great number of research paper. This review presents numerous scientific papers and reviews on the subject of biodegradation of plastic waste.