PlayStation and Xbox users have suffered cyber attacks before, but the most recent incident is by far the most severe. Back in 2014, hackers leaked the details of 13,000 PlayStation users.
Security experts warned players to be extra vigilant when entering personal information into such websites, and that anyone who thinks they have been affected should change their passwords immediately.
"This data is likely to be sold on the dark web and used for future cyber crime," said Robert Capps, vice president of security at NuData Security. "Keep alert to any phishing scams that may appear in email as a result of this hack, changing passwords on any site where same password or username are used.
"It's good to remember to choose unique passwords on all sites that require registration."
It isn't clear who was behind the attacks or if the sites knew about the breaches when they occurred two years ago.
Breach alert website HaveIBeenPwned reports that around 1.3 million account details were taken from the PSP ISO forum and 1.2 million from the Xbox360 ISO one.
Gamers worried that their information could have been taken can check by entering their email address into HaveIBeenPwned's tool that tells users if they have an account that has been compromised in a data breach.
The database, compiled by security researcher Troy Hunt, contains details of more than 2 billion compromised accounts.
The PlayStation and Xbox news follows a string of high profile data breaches that have resulted in billions of people's personal information being leaked online.
Some of the most notable recent incidents include the Adult Friend Finder Networks, Three Mobile and Yahoo breaches.
