A method and system for securing card payment transactions using a mobile communication device provides improved security in card payment transactions such as credit and debit card transactions. Upon receipt of a transaction at the card issuer or other service provider, a message is sent to a mobile communication device that has been uniquely associated with the card. The message may be an interactive message requiring response by the card owner for authorization, or may communicate a one-time-use personal identification number (PIN) with required PIN return via the point-of-sales system or the mobile communications device. In each transaction, the card issuer or service provider confirms that the communication was received and the transaction authorized by the card owner, further ensuring the authorized use of the card. The PIN and/or interactive message response period may be voided after a short time, further improving security of the transaction.