Gourmet Burger Kitchen recorded operating losses of £7.8m in the 12 months ended 28 February 2018, its parent company Famous Brands has revealed.
The casual dining chain's losses were put down to an "adverse macro-economic environment in the UK".
South African franchiser Famous Brands, which also owns Wimpy and Paul, has said that "interventions being implemented in the business" are expected to see it return to profitability in the medium term.
Famous Brands acquired the burger chain in 2016 for £120m.
Launched in 2001 in south London, GBK was founded by three New Zealanders and acquired by the YellowWood Group in 2010.