Listed firms have been reported by regulators to be tangled in financial scandals that have made the quality of their financial reports doubtful due to inadequate control systems of risk assessment, monitoring, information and communication, control environment and control activity. This study examines the relationship between financial reporting quality and the internal control system of listed firms in Nigeria. The research relieda hybridixed approach that sourced primary and secondary data using a bilateral convergent paralleled mixed design. The research method adopted is the interpretive post-action multiple case study that employs reduction and multiple regression as its data analysis techniques. Comparatively, results from both sources of data indicate that internal control system components are determinants of financial reporting quality. One of the implications of the findings on practice is that having financial and accounting experts on the board of directors that uses such expertise on risk assessment inhibits not achieving reporting quality. The study concludes that risk assessment improves financial reporting quality and recommends more such experts on the board of Nigerian firms.