<p>Microalgae are versatile microscopic organisms widely utilized in industries such as food, cosmetics, pharmaceuticals, and aquaculture feed. Their potential extends to alternative applications when cultivated in contaminated effluents, where direct use for food is unsuitable. Also, microalgae residues from biofuel production, wastewater treatment, and nutraceutical extraction can be valorized into biochar which is a stable carbon-rich material produced through processes like pyrolysis, hydrothermal carbonization, and gasification. It has shown promise applications in carbon sequestration, soil fertility enhancement, and environmental remediation. This approach not only adds value to waste streams but also enhances the sustainability of microalgae-based systems. Despite these advantages, challenges in biochar production from microalgae persist. High energy demands, variability in feedstock quality, and the need for optimized production processes hinder large-scale implementation. Economic feasibility and integrating biochar production with existing microalgal biorefineries need to be explored more. Moreover, consistent biochar quality and scalability must be addressed to unlock its full potential. This review highlights recent advancements in biochar applications, including hydroponics, wastewater treatment, catalysis, energy storage, and the development of composite materials. While existing literature discusses biochar’s uses, a comprehensive review aligning these applications with emerging trends is lacking. Addressing production challenges through innovation and system integration can significantly advance the adoption of microalgal biochar as a sustainable resource with environmental benefits.</p> Graphical Abstract <p></p>