Yes, of course there is! KBC and Bancontact have both developed an app to enable very easy mobile payment. You can read more about this on the following pages:

KBC : https://www.kbc.be/retail/en/products/payments/self-banking/on-your-smartphone/mobile/payments-and-transfers.html?zone=topnav#webshop
Bancontact : https://www.bancontact.com/en/bancontact-app/pay-online

You can also complete mobile payment via iDeal.