The present disclosure is directed to a system and method for wirelessly executing financial transactions. A payment card includes an interface, a communication module, secure memory, a user-interface module, and a processing module. The interface connects to a slot of a mobile host device. The communication module wirelessly receives RF signals from and transmits RF signals to a retail terminal. The secure memory stores user credentials and a payment application used to execute financial transactions with the retail terminal. The user credentials and the payment application are associated with a financial institution. The user-interface module presents and receives information through the GUI of the mobile host device. The processing module executes the payment application using the user credentials in response to at least a transaction request received by the communication module and transmits a transaction response to the retail terminal based, at least in part, on the executed application.