<p>This article provides a critical and historical reappraisal of the concept of open innovation, challenging the prevailing narrative that portrays it as a novel managerial breakthrough. Adopting a historiographical-genealogical approach, it traces the intellectual, institutional and empirical origins of open innovation across various academic disciplines, such as economics, management studies, organisational theory and the history of technology. Rather than representing a radical departure, open innovation emerges as a selective synthesis of long-standing insights from economic liberalism (Schumpeter, Hayek), firm theory (Penrose), entrepreneurial history (Chandler, Mowery), strategic management (Teece) and innovation studies (Freeman, Pavitt, Rothwell) among others. The analysis emphasises how Cold War technological infrastructures, networked organisational forms and shifts in R&amp;D collaboration practices during the 20th century laid the groundwork for what would later be codified as open innovation. Particular focus is given to the contributions of authors and projects—such as Project SAPPHO or von Hippel’s user innovation—that foreshadowed key components of the open innovation framework. It also explores how, during the 1990s and 2000s, managerial discourses rearticulated these ideas under a firm-centric, entrepreneurial ethos, turning open innovation into a strategic imperative aligned with neoliberal governance and performance rationales. By reconstructing this lineage, the article reveals the ideological continuities embedded in open innovation discourse, questioning the historical framing often adopted in academic, managerial, and policy circles. In doing so, it contributes to critical innovation studies, offering a more situated, reflexive and historically grounded understanding of how innovation concepts evolve and gain legitimacy.</p>