The question of gender equality in governance has gained prominence in contemporary debates on democracy, political representation, and institutional legitimacy. Existing literature predominantly assesses women’s political participation through descriptive indicators such as the proportion of women in legislatures, cabinets, and local governments. However, these measures are limited as they do not account for whether women possess substantive political authority or influence in decision-making processes. This study argues that numerical representation alone is insufficient for evaluating genuine gender equality in governance. It introduces and develops the concept of Gender Legitimacy as a broader analytical framework. The primary objective of the research is to examine the relationship between gender, power, and governance by moving beyond conventional representation metrics. Adopting a qualitative and comparative research design, the study is grounded in political theory, feminist institutionalism, and democratic governance literature. It conducts a comparative analysis of four democratic contexts: India, the United States, Sweden, and Rwanda. These cases were selected to capture variation in institutional structures, political culture, and levels of women’s political participation. The central contribution of this paper is the development of the Gender Legitimacy Index (GLI), an original multidimensional framework to assess gender equality in governance. The GLI comprises five dimensions: Descriptive Representation, Substantive Influence, Institutional Power Distribution, Policy Responsiveness and Outcomes, and Societal Acceptance and Political Culture. Unlike existing approaches that focus primarily on numerical participation, the GLI evaluates whether governance systems provide women with genuine authority, decision-making capacity, and institutional legitimacy. Findings from the comparative analysis indicate that higher levels of women’s representation do not necessarily correlate with greater political power or democratic equality. Meaningful gender equality is contingent upon the interaction of institutional design, political culture, policy outcomes, and societal recognition, rather than representation alone. The study concludes that Gender Legitimacy should be recognized as an essential dimension of democratic legitimacy. The GLI is proposed as a practical tool for future comparative research and for evaluating public policy aimed at achieving substantive gender equality in governance.