<p>Bioplastics are increasingly used as sustainable alternatives to conventional plastics, aiming to reduce fossil fuel use and pollution. However, concerns have emerged regarding their accumulation in waste streams and the complexities of their treatment. Although promoted for biodegradability, many bioplastics degrade poorly in real conditions, particularly under anaerobic environments. This review investigates anaerobic degradation mechanisms for bioplastics such as PLA, PHAs, and starch-based polymers. We analyze physicochemical properties that influence biodegradability, including crystallinity, molecular weight, and additives. Environmental factors like temperature, pH, retention time, and microbial composition are also reviewed. Special attention is given to pretreatment strategies—mechanical, thermal, chemical, and biological—that enhance hydrolysis and digestion efficiency. The paper compares lab- and pilot-scale studies and considers implications for full-scale applications. We highlight knowledge gaps and propose future directions for integrating anaerobic bioplastic treatment into circular economy frameworks. This review supports informed, sustainable waste management by critically examining the fate of bioplastics in anaerobic waste treatment systems.</p> Graphical abstract <p></p>