The high street retailer will open four stores by the end of the year in Wrexham, Great Yarmouth, Livingston and London's White City.
It also has more store openings planned for next year. Biss Lancaster will run consumer PR campaigns around the openings.
The team is being led by board director Melissa Hinds. She reports into Debenhams head of PR Ed Watson.
Watson joined the retailer in July with a brief to evolve the consumer perception of the brand. He worked with Biss Lancaster in his former role as head of PR for Asda.
Debenhams is currently in the press after the financial collapse of Iceland badly hit its stakeholder Baugur.
Debenhams uses FD for financial PR and Bryan Morel PR for product placement.