Organizations increasingly leverage crowdsourcing and open innovation to tackle complex challenges by engaging external participants. However, maintaining active participation and ensuring high-quality contributions remain significant challenges. Through a structured literature review, this paper systematically examines the theoretical foundations and practical mechanisms that drive participant motivation in crowdsourcing initiatives. We categorize practical indications from research into three key dimensions: platform design and governance, contest design, and solver inducements. In addition to identifying research gaps, this study highlights theories and methods that have received limited attention to date and explores emerging research areas, such as the involvement of older people, the need for better filter mechanisms, and AI-supported collaboration, which warrant further development. Synthesizing theoretical and empirical perspectives, we advance academic discourse on crowdsourcing and digital platform management while providing actionable recommendations for designing more effective, motivation-driven crowdsourcing initiatives.