The study empirically examined dynamics of Treasury single account on performance of deposit money banks in Nigeria. The survey design was suitable because the study requires an accurate examination of the dynamics of TSA on the Nigerian banking industry The population of the study was made up 65 management staff selected from six banks in Calabar, Cross River state, Nigeria. Simple regression analysis containing ordinary least square (OLS) analysis was adopted with the aid of SPSS version. Data were collected from staff of the selected banks; it was discovered that: The implementation of Treasury Single Account has significantly influenced the performance of deposit money banks in Nigeria. The study recommended that banks should avoid armchair activities’ by meeting their customers where they are. They should reduce concentration given to government funds and go out to source funds from other sectors of the economy. Finally, banks should adapt swiftly and look inwards to face the core functions for which they were licensed for.