This study examined the relationship between corporate governance and organisational performance in commercial banks in Rivers State, Nigeria. Cross sectional research design was adopted in studying twenty two (22) of these institutions. Our respondents were managerial employees constituting the population of the study. From the field survey, we retrieved and analysed seventy nine (79) copies of questionnaire from the participants; Kendall’s tau_b correlation coefficient statistical tool was used to determine the relationship existing between the variables while the p-value obtained were used to test hypotheses developed for the study, partial correlation was adopted for the multivariate level analysis to ascertain the moderating effect of organisational culture on the relationship between the predictor and criterion variables. Findings revealed the existence of significant relationship between the dimensions of corporate governance namely; board ability and board reputation and the measures of organisational performance given as employee retention and customer retention and that organisational culture significantly moderates the relationship between the variables. It was then concluded that ability and reputation of board members of any given business organisation in our case – commercial banks greatly influence the performance of these institutions. This gave rise to our recommendations for the banks and other business organisations operating in this era of heightened competitiveness; that they should look critically into the ability and reputation credentials to ensure the board can deliver to the organisations that which is expected to keep the firm in a strategic position before her rivals, keep her competitive and sustainable; as any organisation that cannot meet up to these demands will be found wanting and may go extinct in the nearest future.