The retailer had previously worked with Oxford's Bottle PR – the UK's 113th biggest PR firm according to the 2015 PRWeek UK Top 150 – for more than seven years.
The account, which begins this month, was won by FHF after a competitive pitch at the end of last year, with Bottle MD Natasha Hill telling PRWeek her agency "decided not to repitch for the Poundland account due to a number of reasons".
Poundland has more than 600 stores in the UK – and opened five in Spain last year – and surpassed £1bn turnover for the first time last year. When Bottle took on the account, there were just 153 Poundlands nationally.
FHF director and co-head of brand marketing Isabel Wood said: "Poundland is a fantastic brand and its growth and commitment to the UK’s high streets make this such an exciting time to begin this next chapter together. In addition to running a full-service press office, we will be focusing on creative campaigns that communicate Poundland’s exciting new ranges, product launches and milestones throughout 2016."
Gill Stewart, head of marketing, space and customer at Poundland, said FHF "stood out with its creativity and execution of the brief".
This is the latest win or renewal for FHF, which was formed in a merger in the autumn. It has used these wins to emphasise what it says are the strengths of the new agency.
The merger brings together more than 200 UK consultants and an international network of more than 2,500 employees and 85 offices.
The listed retailer also continues to work with Citigate Dewe Rogerson on financial PR.