The global transition toward sustainable energy systems has intensified the search for eco-friendly and cost-effective methods of hydrogen production. This review explores an integrated approach utilizing naturally available biowaste as multifunctional materials for (i) green hydrogen generation, (ii) high-performance anode development, and (iii) efficient photothermal absorption. Biowaste-derived carbonaceous materials were synthesized via pyrolysis and surface activation, yielding porous structures with high surface area, excellent electrical conductivity, and abundant functional groups. Biowaste-based biochar has emerged as a pioneering material for green hydrogen production and as a high-performance anode material for energy storage. However, challenges such as optimizing production under production constraints and scaling up need to be addressed to make biowaste-based biochar a viable and sustainable option. This review explores the effects of biowaste type and operating conditions on biochar properties and outlines future research directions to enhance its practical application in hydrogen production and anode material synthesis.