Extant research in comparative politics has examined the role of institutional frameworks such as constitutional design, the nature of the electoral systems, parliamentarism and federalism on the quality of governance. Understanding variations on effective democratic governance has assumed a state-centric approach that has largely neglected how strong legislatures can drastically affect political outcomes. This study finds empirical evidence that the strength of national legislatures (in terms of its influence over the executive, institutional autonomy, its specified powers and institutional capacity) is correlated to effective democratic governance as measured by voice and accountability, governmental effectiveness, regulatory quality, control of corruption and rule of law entrenchment based on a cross-national analysis of 150 countries with available data from the period 1996–2016. The results hold even when the sample is restricted to developing countries, where party systems are more likely to be under-institutionalized. A sensitivity analysis also confirms that the relationship between strong legislatures and effective democratic governance is not attenuated or conditioned by its interactive effect with other institutional arrangements. Implications suggest that the substantive strength of national legislatures promotes higher levels of democratic accountability, and that the international community must focus on frameworks that strengthen global legislatures to avert political instability and creeping authoritarianism.