The sustainable management of organic waste is a critical global challenge, leading to greenhouse gas emissions and resource inefficiency utilization. Bio4UP tackles this by developing biochar-enhanced technologies within a zero-waste strategy, integrating biotechnological and catalytic approaches in a circular economy framework. The project aims to: (1) Develop multifunctional biochars for organic waste valorization; (2) Optimize biochar-integrated processes in anaerobic digestion, biogas purification, and catalytic CO2 conversion into methanol or methane to improve efficiency and sustainability; (3) Valorize biochar-containing digestate into biopesticides and biostimulants via solid-state fermentation; (4) Develop decision-support tools and sustainability frameworks to guide circular economy strategies; and (5) Foster interdisciplinary, intersectoral, and international collaboration through staff exchanges and knowledge transfer. Bio4UP aligns with MSCA SE principles by bringing together 9 European beneficiaries (Spain, France, Ireland, Greece, Slovenia) and 2 Latin American partners (Colombia, Peru) from academia, industry, and research institutions. The project mobilizes 302 person-months of staff exchanges, fostering expertise in biochar engineering, process optimization, and sustainability assessment while promoting mutual knowledge exchange between Europe and LMICs. By integrating lab-scale research with pilot-scale validation, Bio4UP bridges scientific innovation and industrial application, supporting the European Green Deal and Horizon Europe’s circular economy objectives. The project advances scalable waste-to-resource pathways, enhancing bioenergy production, reducing emissions, and fostering sustainable agriculture in alignment with the Sustainable Development Goals, while strengthening researcher mobility and career development.