This study examined the effect of money market deposit rates on the profitability of quoted commercial banks in Nigeria using time-series data from the Central Bank of Nigeria Statistical Bulletin and cross-sectional data from the audited financial statements of the banks. Return on Assets (ROA) was modeled as a function of the three-month, six-month, twelve-month, and over twelve-month money market deposit rates, with estimation carried out using the Ordinary Least Squares technique within a panel data framework. The empirical results revealed a significant relationship between money market deposit rates and bank profitability, with approximately 53.3 percent of the variation in ROA explained by changes in deposit rates. The findings further showed that all money market deposit rate categories exerted a positive influence on ROA, except the twelve-month deposit rate, which had a negative effect. The study therefore concludes that money market deposit rates are important determinants of the profitability of quoted commercial banks in Nigeria and recommends that the Central Bank closely monitor and adjust monetary policy rates to ensure price stability, promote stable deposit rates, encourage savings and investment, and support structural reforms that enhance money market efficiency, reduce banks’ operating costs, and curb inflation.