The objective of the study was to examine the financial appraisal of online banking on the Deposit Money Banks in Nigeria between 1991 and 2015. The study adopted Fully Modified Ordinary Least Squares (Fully Modified OLS) to measure the relationship among the variables. The finding of the study showed that interaction of online banking and Deposit Asset Ratio has positive significant impact on the profitability of the Deposit Money Banks in Nigeria in the long run. In addition, the finding of the study showed that interaction of online banking and Loans to Asset Ratio has significant impact on the profitability of the Deposit Money Banks in Nigeria in the long run. The ECM was correctly signed and significant at 5% level of significance. The speed of adjustment of the ECM was 134.72%.  Lastly, the short run showed that loan to asset ratio and inflation were significant at 0.05 level of significance. The study therefore recommends that Deposit Money Banks should intensify effort on the adoption of online banking.