The system, which allows mobile developers to receive an age rating for their game in minutes as part of an app's submission process, has been previously supported by Microsoft and rolled out for Windows Phone 7 earlier this year.
"Windows 8 Mobile has already signed up to use PEGI Express, to include their apps under the ratings system," UKIE president Jo Twist told Digital Spy. "So I think that's a big move, and once one platform holder like that goes down that line, hopefully others will follow."
Twist said the digital ratings system is being "extended" and hopes that PEGI will be used as the single rating system for all platforms, including Apple's iOS.
"I think there is a challenge in terms of the many different devices and platforms and the way in which people are playing games," she said.
"A lot of games that you still buy in a shop that have a PEGI rating, or buy online or download online, have got the PEGI rating, or those that have an online extension, which would be rated under the same system.
"Apple has their own approval system and it would be great if PEGI became the single system for all platforms one day."
When asked how it would be possible for Apple to adopt the system, Twist replied: "I think it's making sure we communicate that it is effective, but it is already effective.
"Now we're in the situation where it's the single, relevant rating for games, then we can start to show how effective it is, how it's good that the industry takes its responsibilities seriously."
This week PEGI became the sole classification system in the UK, one that is legally enforceable by the law.
The changes come more than three years after a government report favoured PEGI ahead of the BBFC in the battle to provide a simpler rating system.
PEGI was also backed by a member of the European Parliament when the debate began in 2009.
Windows Phone 8 will launch later this year.