Lawson Dodd is to promote the appeal, which aims to raise money for building work at the west London hospital.
As an independent organisation, the Royal Hospital Chelsea - currently home to 320 veteran soldiers - has to fund new projects privately, and is hoping to hit its target by March 2008. The cash will be used to build and equip a new infirmary and upgrade the rest of the living accommodation.
Appeal director Roy Ratazzi said there were a number of activities and events planned over the next year that needed PR support.
Army units will be embarking on runs, triathlons and other sponsored activities to raise money, while pensioners armed with collecting boxes will be visiting events across the UK to support the appeal.
Lawson Dodd joint MD Joanna Dodd said the agency was planning a campaign to publicise the appeal and raise awareness of the UK-wide events programme.
'We will cover a broad range of broadcast and national media,' said Dodd.
'We will also generate awareness of the hospital's role in providing sheltered accommodation, and raise its profile among people who are looking to house elderly parents.'