Artificial Intelligence (AI) is increasingly recognized as a transformative force in innovation processes, yet its potential to advance Open Social Innovation (OSI) remains underexplored. This paper investigates how AI can support the design, implementation, and scaling of OSI projects, which rely on collaborative, cross-sectoral approaches to address societal challenges. Drawing on recent developments in machine learning, natural language processing, and decision-support systems, this study highlights AI’s role in enhancing ideation, facilitating stakeholder engagement, enabling evidence-based decision-making, and fostering inclusive participation. The analysis synthesizes insights from case studies spanning open innovation platforms, civic technology initiatives, social entrepreneurship ecosystems, and AI-driven public value creation in complex, large-scale contexts, and conceptualizes AI’s role in OSI through three interrelated functions: as a prosthetic extension of cognition; as an institutional mechanism; and as an infrastructural element. By outlining a conceptual framework that considers AI as both a technological and socio-organizational enabler of OSI, this study contributes to the emerging discourse on scalable solutions to pressing grand challenges by offering actionable recommendations for the responsible use of AI for social good.