Refurbished handsets are an area of focus for the brand as it attempts to encourage consumer behaviour change.
At the pop-up shop in London's Covent Garden, nothing is for sale. To enter, people must pay with a pledge and commit to choosing refurbished products wherever possible.
Giffgaff has joined forces with Melanie Fisher of Zero Waste Goods for the activity. Fisher has curated a marketplace that makes it easier for people to support planet-friendly brands, find responsible products, and transition to a zero-waste lifestyle.
Visitors to the pop-up will be able to place a pledge for 50 'like new' refurbished phones, plus 50 other refurbished items in tech, wellness, homeware, fashion and accessories.
Items include bikes, a pre-owned games console, a turntable made out of recycled materials, and shoes made from surplus pineapple leaves.
The opening of the pop-up comes after the brand received positive feedback from its members about its range of refurbished phones.
Giffgaff chief executive Ash Schofield said: "When you enter our pop-up store and see the other beautiful sustainable items among our selection of refurbished phones, you really start to realise that not buying new might just be a smarter choice."
The campaign was created with PR agency Mc&T. Matt Crowhurst, associate director at the agency, said people have also been taking to social media to make a digital pledge to choose refurbished goods.
"It's about tapping into changing consumer behaviour and showing that sometimes, something that's 'preloved' can be just as good as something brand new. People are taking to social media to make a digital pledge, chiming with Giffgaff’s wider campaign and focus on refurbished," he added.