Nanobiomaterials are increasingly recognized as essential components for sustainable energy and environmental technologies due to their renewability, partial biodegradability, and generally lower toxicity compared with conventional fossil-derived nanomaterials. This chapter provides an integrative overview of major nanobiomaterial classes, including nanocellulose, chitosan and related biopolymers, and bio-derived nanocarbons such as biochar and green graphene, and relates their structural features, surface chemistry, and processing routes to functional performance. Green and biogenic synthesis pathways, valorization of agro-industrial and electronic residues, and scalable manufacturing methods such as gas-phase processes, electrospinning, and additive manufacturing are examined within techno-economic and life-cycle frameworks. Applied sections highlight the deployment of nanobiomaterials in water and air purification through advanced membranes, tailored sorbents, and catalytic systems capable of removing or degrading organic micropollutants and PFAS. Additional applications include soil and agricultural amendments that enhance nutrient management and pollutant retention, as well as clean-energy technologies such as photocatalytic hydrogen production and bio-derived electrocatalysts for electrochemical reactions. Across these domains, nanobiomaterials frequently match or surpass traditional inorganic or petrochemical counterparts in permeability, selectivity, adsorption capacity, and catalytic activity, while enabling multifunctional integration such as combined pollutant capture and degradation. The chapter also evaluates safety considerations, degradation pathways, and circular-economy strategies aimed at controlled biodegradation, regeneration of carbonaceous materials, and recovery of critical metals. Persistent challenges are identified in reproducibility, regulatory assessment, and long-term material stability under real-world conditions. Overall, the chapter outlines key design principles needed to advance “truly green” nanotechnology grounded in the responsible engineering, evaluation, and deployment of nanobiomaterials.