The sudden announcement of the devaluation of the Nigerian Naira to US Dollar by the Central Bank of Nigeria (CBN) on the 25th November 2014 has created an intense debate and a great deal of mix responses among market analysts and the general populace. However, available opinions on the degree of effects such announcement might have on Deposit Money Banks (DMBs) stock prices can at best be adjudged as a mere presumption and not an outcome of empirical investigation. This study empirically examined Naira devaluation announcement of the 25th November 2014 and share prices of Deposit Money Banks in Nigeria. Employing the standard event study methodology and correlational design on a sample of thirteen out of the sixteen registered DMBs with the Nigeria Deposit Insurance Commission (NDIC) and listed on the Nigerian Stock Exchange that traded on the historic day. The study ascertained the significance of cumulative abnormal return on the fifteen trading days prior to the announcement, day of the announcement and fifteen trading days succeeding the announcement day. The study documented a statistically non-significant cumulative abnormal return of 0.9078 percent on the fifteen trading prior to the announcement. The study also established the presence of statistically significant cumulative abnormal return of 0.6851 percent and 3.0982 percent on the announcement day and fifteen trading days after the announcement. The study concluded that the sudden announcement of Naira devaluation led to positive market reaction by investors of DMBs in Nigeria and the positive trend continued for fifteen trading days succeeding the announcement. The study recommended that import substitution policy should be implemented to ensure persistent of the positive returns as this would encourage an upsurge in the foreign portfolio and increase the liquidity base of the Deposit Money Banks as well as the Nigerian Stock Exchange. This would enhance their readiness to lend to the real sector of the nation‟s economy.