Names, addresses and emails are among the non-financial personal data accessed in addition to the 5.8m cards compromised.
However, it added that the company said it had notified card providers to 105,000 non-EU issued cards which did not have chip and pin technology so those customers could be immediately protected.
The Dixons Carphone share price fell by 5.5% within minutes of major hack announcement.
The company said the probe was continuing, but it had found that there was an attempt to compromise 5.9m cards in one of the processing systems of Currys PC World and Dixons Travel stores.
Alex Baldock, the company's new chief executive, apologised for the data for breach and admitted the firm had failed customers.
In a statement put out today it says a review of its systems and data unearthed the data breach.
It goes on to offer the not-entirely-reassuring reassurance that it has "no evidence to date of any fraudulent use of the data as result of these incidents" before admitting the compromised information included (incomplete, in some cases) payment card data.
"We've taken action to close off this unauthorised access and though we have now no evidence of fraud as a result of these incidents, we are taking this extremely seriously", he added.
'We've taken action to close off this unauthorised access and though we have now no evidence of fraud as a result of these incidents, we are taking this extremely seriously. It said there was no evidence of fraud here either.
The group said it had informed the Information Commissioner's Office (ICO), the Financial Conduct Authority (FCA) and the police about the incident. "As a multinational organisation, Dixons Carphone would have been well aware of the Target breach". It said since the 2015 attack it had worked extensively with cyber security experts to upgrade its security systems.
"The protection of our data has to be at the heart of our business, and we've fallen short here", he said.