GoKawiilMonzo says a technical issue which left users unable to use their card for payments or transfers has now been resolved.
The digital bank had previously posted on X, external it had "identified some issues" and activated a stand-in backup service which meant users could still make transactions like card payments and sending and receiving bank transfers.
However, some users noted under the post, external that Monzo Stand-in was "not working as expected" and they could still not use their card.
Following this, a Monzo spokesperson said all of its services were now "back up and running". "We're sorry for any inconvenience and thank customers for their patience," they said.
The British digital bank was set up in 2015 as a "new kind of bank" that ditched physical bank branches for a mobile-first app.
The firm says it now has more than 16 million personal and business customers which use the service around the world.
As the company worked on the issue, it noted that users would be able to use its independent service Monzo Stand-in to still "make card payments, withdraw cash, freeze your card, send and receive bank transfers, and more".
While the support appears to be working for some, others have still been reporting issues.
"I can't use my card for anything at the moment," posted one X user, external.
"Your "backup" bank does not have the functionality you state it does. I can't make bank transfers right now," said another, external.