Bell Pottinger is understood to have beaten RLM Finsbury in a two-way final pitch for the new brief, which will see it handed corporate, public affairs and media relations work as the bank’s only retained agency.
The appointment comes as the 631-branch bank, which was forced to split from Lloyds last year, prepares for an IPO later this year estimated to be worth around £1.5bn.
Commenting on Bell Pottinger's appointment, TSB head of media relations Charlotte Sjoberg said: "We were looking for an agency that would support us across both our media and public affairs briefs and that would work collaboratively with us. TSB has an exciting year ahead of it having only launched on Britain’s high streets last September and Bell was the perfect choice to help us navigate TSB’s early life as an independent bank, bringing local banking to Britain."
TSB launched as a separate bank last autumn as a condition imposed by the European Commission for Lloyds Banking Group taking a £20bn bailout following the 2008 banking collapse.
John Sunnucks, executive chairman at Bell Pottinger, financial, added: "Against the backdrop of continued controversy in the banking sector, there can be few more interesting challenges in our industry than helping a brand new national high street bank communicate why and how it is different."