In the face of mounting concerns regarding climate change, the circular economy has emerged as a strategic model for reducing the extraction of natural resources and minimizing environmental impacts. One of the pillars of this concept is waste valorization, which converts discarded by-products into materials with high added value. In this context, biochar production stands out as an innovative and sustainable solution, converting wastes through either pyrolysis, hydrothermal carbonization, gasification, or torrefaction into a stable carbonaceous material. The potential applications of biochar are diverse, spanning environmental, agricultural, and energy sectors. Biochar production, therefore, offers a multifaceted approach to addressing the challenges of climate change and promoting the development of a circular economy. In addition, biochar production can be integrated into the context of biorefineries. Therefore, this chapter, through an introductory approach, addresses biochar production processes, possible biochar applications, the potential of biochar production in a biorefinery context, and the advances in biochar research.