The agency will be handling work across the UK, Germany, Ireland and Poland for the store plus corporate comms for its parent company TJX Europe.
Its brief will cover consumer brand PR and press office, social media and content marketing as the retailer seeks to develop comms beyond its core messaging on discount prices.
Richard Kanareck, MD, UK for FleishmanHillard said: "TKMaxx has a very loyal and engaged following, and we’re now looking to build upon that. It has value at the core of its brand, so there is a real opportunity to broaden out from there and extend its appeal."
It is understood that FleishmanHillard was handed the work following a four-way pitch, which initially kicked off last summer and was handled by Oystercatchers.
TJX surpassed $25bn in sales in 2012, an increase of 12 per cent, with TK Maxx outlets numbering 343 in the UK, Ireland, Poland and Germany at the end of the same year.
However the retailer came under scrutiny last month with the broadcast of Channel 4’s Dispatches, 'Secrets of the Discount Stores', in which it was accused of misleading customers over prices.
With the agency’s London office acting as a central hub, it will handle work through offices in each country and report to Deborah Dolce, group brand and marketing director for TJX Europe.