This study examined the effect of tax planning on the financial performance of Nigerian Development Banks. The study covered the period of 2012 to 2019 (post IFRS adoption era in Nigeria). Data were sourced from the annual financial statements and reports of the selected Nigerian Development banks. Pooled regression analysis technique was adopted to establish the effect of effective tax rate, tax savings, intensity of capital and firm size on financial performance of the banks. It was discovered that effective tax rate had negative and insignificant effect on return on equity while tax savings had positive and insignificant effect on return on equity. However, intensity of capital and firm size were discovered to have positive and significant effect on return on equity. The study thus, concluded that tax planning do significantly influence the financial performance of development banks in Nigeria in area of capital intensity and firm size. Thus, there is need for Nigerian Development Banks to effectively explore tax planning strategies in areas of effective tax rate and tax savings in order to reduce tax burden or liability. It is therefore recommended that an established cum effective tax planning unit or firm are needed to help in achieving effective tax planning in Nigerian Development banks in order to enhance more financial performance.