The activation is part of the brand’s announcement that Snapchat is now part of its Go Binge service, the unlimited streaming plan.
The "All you can pug" brunch will take place simultaneously in London and Liverpool on 12 May.
There will be a bottomless brunch menu, and guests will be able to dress up their dogs as Puggerfly, Three’s new mascot.
The experience last 75 minutes and costs £5. This includes one main breakfast dish, bottomless pastries, prosecco and coffee or tea, as well as dishes for dogs. All proceeds will be donated to the Pug Dog Welfare Association.