Open-source innovation now extends from open-source software to open-source hardware, open science, and open-source artificial intelligence. Yet existing explanations remain largely anchored in open-source software, offering limited accounts of changing open-source objects, participation structures, governance arrangements, and value logics. Based on a systematic review of 476 English articles published between 2000 and 2026, this study clarifies the conceptual boundaries, organizational emergence, organizational consequences, and paradigmatic implications of open-source innovation. It argues that open-source innovation is not a simple extrapolation from open-source software, but an organized innovation paradigm through which multiple actors jointly advance knowledge production, technological evolution, and value realization under specific organizational and governance arrangements. The review further shows that object attributes, resource structures, platform positions, and institutional constraints shape its governance forms, boundary relations, and value centers. This study develops an integrative analytical framework comprising condition configuration, collaborative generation, value sustainment, and feedback evolution, thereby providing a theoretical foundation for advancing open-source innovation research from the description of empirical phenomena toward a systematic analysis of innovation paradigms.