<p>This critical review examines algae-derived bioplastics within a circular bioeconomy framework, with primary emphasis on polymer production routes, material properties, environmental performance, and end-of-life behavior. Unlike broader algae valorization reviews, this article focuses specifically on how microalgal and macroalgal biomass can be converted into bioplastic precursors, polysaccharide-based films, polyhydroxyalkanoate feedstocks, and composite materials, while discussing biofuel pathways only where they support integrated algal biorefinery design. The review addresses three key questions: which algal resources and processing routes are most relevant for bioplastic production, what performance and biodegradation characteristics are realistically achieved, and which environmental, economic, and policy barriers most strongly affect scale-up. Particular attention is given to extraction efficiency, blending strategies, mechanical and thermal limitations, life-cycle assessment, techno-economic uncertainty, and the influence of disposal routes, including composting, soil burial, anaerobic digestion (AD), and marine exposure. The analysis shows that algae-derived bioplastics are promising but remain constrained by feedstock variability, processing costs, limited evidence of marine degradation, and limited commercialization, requiring stronger standardization, integrated valorization, and the implementation of scalable circular biorefineries.</p>