The urgent need for innovative solutions to global environmental challenges has driven the convergence of biology and nanotechnology, resulting in the emergence of bionanotechnology as a transformative force. This comprehensive review paper explores the fundamental principles, applications, benefits, and potential risks associated with harnessing bionanotechnology to advance environmental sustainability. Beginning with an elucidation of the fundamental concepts underlying bionanotechnology, this paper establishes the synergy between biological systems and nanomaterials. The unique properties of nanomaterials, coupled with the adaptability of biological processes, form the foundation for a diverse array of real-world applications. Focusing on applications, the paper highlights how bionanotechnology addresses critical environmental issues. It showcases case studies that exemplify its impact on water purification, air quality improvement, waste management, renewable energy production, and more. These case studies underscore the tangible benefits and efficacy of bionanotechnology in tackling complex challenges. However, as the potential of bionanotechnology is harnessed, it is crucial to navigate potential ecological risks. The paper emphasizes the importance of ecotoxicological considerations, discussing how nanomaterials interact with ecosystems and organisms. Ethical and responsible development of bionanotechnology, informed by these considerations, ensures that its benefits are maximized while minimizing potential harm. In conclusion, this review paper underscores bionanotechnology's potential to revolutionize environmental sustainability. By fusing the power of nanomaterials and biology, bionanotechnology offers a holistic approach to address pressing global challenges. While celebrating its transformative promise, the paper emphasizes the need for a balanced approach that safeguards environmental health. As society looks towards a more sustainable future, bionanotechnology stands as a pivotal paradigm for shaping an environmentally conscious world.