Can debit cards be used to make mortgage payments in the United States?

A debit card will deduct the amount from your bank account, so you must be having the balance in your account. Why not simply write a check.

To answer your question - Yes, if only your mortgage company would accept online credit/debit card payments.

Alternatively, you can get a cash advance out from any bank and use that money to pay via either a direct deposit or money order/certified check.