Research on media framing of energy-transition technologies has expanded across technologies and national contexts, but cumulative comparison remains difficult since studies conceptualize and operationalize “frames” in markedly different ways. This systematic review synthesizes 93 peer-reviewed studies of journalistic and news-media coverage to examine recurring framing structures, cross-technology and cross-national variation, temporal dynamics, and the explanatory capacity of existing designs. An iterative, theoretically informed harmonization identifies eight substantive frame domains: technofunctional performance, material-economic viability, ecological-climate consequences, governance-institutional capacity, energy-system security and geopolitics, health and safety, social-distributive justice, and socio-cultural or place-based compatibility. These domains are analytically distinct from evaluative orientation, transition-pathway positioning, and communicative form. Comparative evidence shows recognizable interpretive repertoires across technologies, but their salience, orientation, and linkage vary across energy systems, policy trajectories, implementation stages, journalistic settings, and event periods. The literature accumulates descriptive patterns more securely than independent technology, country, policy, or event effects. This study therefore proposes a review-derived framework for analyzing the media construction of socio-technical legitimacy as legitimacy-relevant representation rather than an audience or institutional outcome. Cumulative progress requires strategically comparable designs that distinguish substantive domain, orientation, pathway position, sponsorship, and journalistic organization.