The retailer currently has 12 stores in the UK, but reportedly hopes to open more than 100 stores.
Frank, which won the business via a competitive pitch process, will look to raise the profile of the brand and its offering, while generating awareness for its new e-commerce platform.
The agency will also lead a wider consumer press office programme for its seasonal and bespoke products.
Clas Ohlson started as a mail order company in Sweden in 1918. It is now Sweden’s biggest home and hardware chain and the country’s third biggest retailer overall.
The brand first entered the UK market in 2008, offering more than 10,000 products in each of its 12 stores across home, multimedia, electrical, hardware and leisure.
The retailer used TLG to support its UK launch and subsequent store openings.
Charlotte Turnbull, marketing manager, commented: "We are thrilled to be working with Frank PR to maximise the opportunities we see in Clas Ohlson. We’ve been in the UK for more than three years and we feel now is the time to really strengthen our position in the UK market.’