Biocomposites composed of the polymeric matrix and reinforcing fibres have emerged as new innovative materials with multiple applications and as an alternative to traditional composite materials. To be classified as biodegradable and green, biocomposites need to align with the green chemistry principles which are part of the sustainability concept. This review presents the recent advances in biocomposite development and discusses how these satisfy the green chemistry principles to position biocomposites as green and sustainable materials. Special attention is paid to the aspects of their sourcing, synthesis and modification methods, and preserved biodegradation and/or recyclability qualities to fulfil favourable end-of-life options. Furthermore, the design of poly(lactic) acid– and mycelium-based biocomposites is presented in case studies to discuss the above aspects.