The role of financial development in the growth and development of developing economies have constituted a popular discourse among development and financial economist. Two key issues of interest in the discussion of financial are competition and concentration in the banking industry as key predictors of growth in every economy. This study therefore investigated the effect of concentration and competition in the Nigerian banking industry on economic growth with focus on the big-8 banks in Nigeria. Moreover, the implementation of the consolidation policy of the Central Bank of Nigeria in the year 2005 informed the choice of period (i.e., 2005-2019) selected for this study. While a positive concentration-growth nexus was found in the study, the study could not establish a positive competitiongrowth nexus in the Nigerian economy for the period under review. The increase in capital base as required by the consolidation policy has accounted for the level of concentration in the banking industry; and this has made it easier for banks to contribute significantly to the growth of the economy. Imperfect competition in the banking industry on the other hand has led to higher costs of loans that detain firms from new investments, thus slowing down the firms' expansions and productivity growth.