This paper investigates the effectiveness of CAMELS (Capital Adequacy, Assets Quality, Management Efficiency, Earning Efficiency, Liquidity and Sensitivity to Market Risk) based supervision in risk management of A class commercial banks. The riskiness is measured by Downside Deviation (i. e., volatility of returns below minimum average return) and Standard Deviation of ROA and ROE. Using the Generalized Method of Moments (GMM) in secondary balanced panel data during major financial development (i. e., 2004 to 2018; BASEL-I-II-III) of all 28 commercial banks of Nepal; causal relationship between supervision and risk management has been investigated. The result shows that the commercial banks in Nepal can reduce their downside deviation as well as standard deviation of ROA and ROE by reducing the Non-Performing Loan (NPL), maintaining appropriate liquidity and by increasing management efficiency. Further, results justifies the relevance of risk based supervision adopted by central bank and interest spread set. However, increased capital base has not helped in reducing riskiness of banks. Overall, the study finds that among the six parameters of supervision (i. e., CAMELS), five parameters (i. e., AMELS in the priority order of AMLSE) are capable enough to reduce the riskiness of commercial banks if maintained strictly as guided by the central bank.