The firm identified the breach on Friday and started contacting current and recent customers on Saturday.
Data stolen includes names, email addresses, home addresses, phone numbers, the last four digits of card numbers and bank account numbers and sort codes.
The lender said customers’ accounts were now secure.
A further 25,000 customers in Poland have also been affected.
Wonga is still in the process of contacting all customers who have been impacted.
A company spokesperson, said: “Wonga is urgently investigating illegal and unauthorised access to the personal data of some of its customers in the UK and Poland. We are working closely with authorities and we are in the process of informing affected customers. We sincerely apologise for the inconvenience caused.”
What should Wonga customers do next?
- The payday lender says accounts are secure and customers do not have to take any action. But if you are concerned, you should change your Wonga.com password.
- Wonga says customers should be “extra vigilant” and keep a close eye on other accounts and online activity.
- The firm suggests contacting your bank and asking them to look out for any unusual activity.