Uniqlo parent company Fast Retailing is the latest retailer to endure a data breach.
Hackers could have gained access to 461,091 accounts on Uniqlo's Japanese shopping websites, the company has announced.
It is understood the move does not affect Australian accounts.
Hackers may have accessed customers’ personal information, purchase history and partial credit card numbers.
The breach could affect users of its Uniqlo Japan and GU Japan online stores, from April 23 to May 10.
The hack has been classed as 'list type' account hacking, where user IDs and passwords are potentially leaked from other services or sites.
The company said it is still investigating the breach, with the number of incidents and circumstances potentially changing throughout the course of the investigation.
Fast Retailing has advised online customers to use unique passwords and to avoid using passwords used from other websites to lower the chances of hackers accessing their accounts.
Consumer data security has become a growing concern for retailers, with Kathmandu announcing a breach in March.