In a letter to customers, Mr Hutson apologised and advised customers to “remain vigilant for any emails that you are not expecting that specifically ask you for personal or financial information, or request you to click on links or download information”.
The hack happened between 15 and 17 June on the pub chain’s old website, which has since been replaced.
Mr Hutson said there was no evidence that fraudulent activity had taken place using the hacked data and the database did not hold passwords.
He added: “We have taken all necessary measures to make our website secure again following this attack. A forensic investigation into the breach is continuing.”
The data accessed was held by a third party company but had remained undetected. Wetherspoon became aware of a possible breach on 1 December and it was confirmed the following day.
Information would have been put on the database either when customers signed up to receive Wetherspoon’s newsletter, registered with The Cloud to use wi-fi in their pubs, submitted a ‘contact us’ form on the website, or bought vouchers online before August 2014.