This study examined the legislature-executive crisis in Nigeria under the APC- led democratic governance between 2015 and 2019. The objective was to understand the factors that animated the crisis and its implication on good governance. To achieve this, the study relied on the descriptive qualitative approach and the institutional theory of conflict to create linkage and consolidate the findings. It used mainly secondary data like textbooks, journal articles, legislature-executive documents, and the 1999 Nigerian Constitution. From the analysis, several factors emerged which included leadership interference and parliamentary oversight. Others were poor capacity building, corruption, and absence of enough communication. By implication, the result showed that between 1999 and 2015, the parliament passed 248 bills into law, but passed 213 bills between 2015 and 2019. However, information also appeared that the crisis impacted more negatively on the institutions’ relations and the political system. It disrupted the democratic ethics of accountability, transparency, and equitable distribution of resources. Public policies like lawmaking, oversight and implementation suffered greatly. Unnecessarily delayed budget proposals increased poverty, economic deprivation, and instability. Positive changes promised by the APC government were lost in the crisis and these were all against democratic ethos. Based on the ongoing, the study concluded that democracy and good governance can be strengthened when the institutions collaborate better to execute their roles, respect their institutions and the 1999 Constitution. The study would benefit the institutions, the public and researchers. Further study is also needed on the judiciary-legislature pattern of relations under Nigeria’s fourth republic democratic governance.