Where can I use my Onsi Card? Matt Owen 04 October 2023 09:16 Updated You can use your Onsi Card at all shops (in store and online) where Mastercard is accepted, apart from a few prohibited merchants. Related articles Do I need a credit check to get an Onsi Card? What benefits does Onsi offer? Can I pay bills with my Onsi Card? Can I use my Onsi Card to buy vouchers on the Onsi website? How? Is there a cap on how much cashback I can earn?