Abstract: A system and method are provided for performing a secure ATM debit transaction for a buyer making a payment to a seller over the Internet. The system comprises an ATM debit network, a seller web site, a transaction computer system, and a software program. The ATM debit network links together a plurality of banks, financial institutions, and ATM machines. The seller web site is accessible to the buyer via the Internet. The transaction computer system is adapted to be communicably coupled to the seller web site and the ATM debit network as needed to perform the secure ATM debit transaction. The software program on the transaction computer system is adapted to authorize and facilitate the secure ATM transaction between the seller and the buyer using at least one digital certificate. When the secure ATM transaction is authorized by at least authenticating the at least one digital certificate, the software program submits a debit request to the ATM debit network corresponding to the secure ATM debit transaction.