GBK is to introduce a new brand identity nationwide by 2014, as its Ealing and Wimbledon sites become the first to be fully rebranded.
GBK started working with marketing consultancy Figtree Prophet earlier this year in a bid to undertake the first full brand redevelopment exercise since the chain was founded in 2001. The company has also been quietly refurbishing many of its 59 restaurants, although the new logos and signage have only been introduced to Ealing and Wimbledon so far.
The burger chain is moving away from its original Australasia-heavy themes to what it said would be a more youthful and premium positioning.
As part of the changes, it is to introduce a new logo, motifs and colour palette along with revamped interiors including open kitchens and artisan design features.
Katie McDermott, marketing director of GBK, said: "All of these new elements are a reflection of an 18-month drive to develop and improve our food, customer experience and employee culture.
"The first of our kind, we have grown rapidly over the last 12 years, increasing the number of our restaurants more than tenfold within a decade. But, as the market becomes more competitive, we can't rest on our laurels and need to always be looking at ways to up our game - we knew it was time to take a step back, take stock, and define a clear path for our future.
"We have made some significant operational changes; both behind the scenes and front of house, building on the step-change in food quality already seen over the last two years. The refreshed identity will enable us to firmly establish the new approach."
In addition to the new appearance, GBK said it would underline its premium positioning with a move away from discounts and offers in favour of loyalty activity, including rewarding customers through the GBK App. Launched in November 2012, the app has had over 180,000 downloads to date and rewards customers based on visit frequency and spend.
GBK will launch its full rebrand campaign in January 2014. It currently has 59 restaurants and is owned by Capricorn Ventures, which also owns Nando's.