Current energy shortages and environmental crises have compelled researchers to look for inexpensive and sustainable resources that can be obtained via environmentally friendly routes to produce novel functional materials. Biomass has been identified as one of the promising candidates given its availability in large quantities and renewable nature. Among the various feasible synthetic strategies, hydrothermal carbonization (HTC) has been admired for its energy efficiency and ability to synthesize carbonaceous materials for use in a wide range of applications. In this review, the different types of biomass and strategies available for the synthesis of carbon-based materials are discussed. Furthermore, factors influencing the efficiency of each strategy are analyzed and evaluated. Subsequently, the utilization of carbonaceous materials in environmental, catalytic, electrical, and biological applications are reviewed to further demonstrate their functionalities across different fields. Copyright © 2019 American Chemical Society.