<p>Plastics (synthetic polymers) play an essential role in modern living, but their uncontrolled disposal has led to severe environmental impacts. The production of plastics is based on fossil feedstocks, which are associated with detrimental climate effects. Thus, sustainable concepts for the re- and upcycling of plastic waste are urgently required. Biotechnological approaches have recently emerged as innovative alternatives to conventional methods. Engineered ester hydrolases have enabled large-scale industrial recycling of the abundant polyester polyethylene terephthalate through monomer recovery, and recently discovered novel enzymes can depolymerize other plastics with hydrolyzable backbones. For plastics with only saturated carbon–carbon bonds in their backbones, such as polyolefins and polystyrene, a chemo-biotechnological process appears to be a viable option, where engineered microorganisms can metabolize small-molecule products from a (thermo)chemical polymer deconstruction to produce value-added products. Here recent achievements using biocatalytic and biotechnological methods are discussed.</p><p></p>