This study seeks to evaluate the contribution of capital market to the economic growth in Nigeria using a time series data from 1999 to 2017. The main aim of the study is to investigate if total market capitalization before and after the introduction of Central Security Clearing System in the capital market affect economic growth in Nigeria. To achieve this objective, an econometric model was formulated and an Ordinary Least Square method was used in the study. The annual time series data used in the study were adjusted with the Jarque-Bera test of normality to remove spurious OLS regression result. The findings revealed that market capitalization has a positive effect on economic growth in the post Central Security Clearing System and a negative effect in the pre Central Security Clearing System and the coefficient of determination in the post Central Security Clearing System is very high when compared to the pre. The t-calculated value for Market Capitalization (MCAP) is 0.5895 in the post Central Security Clearing System and when compared with 5% statistical value (0.5895>0.05, it indicates that the alternative hypothesis should be accepted and also that market capitalization in the post central clearing system affect economic growth in Nigeria.