WDMP won the business following a pitch against undisclosed agencies and will now be responsible for creating a range of digital and direct marketing activity that aims to raise awareness of the services that Companies House provides.
The agency will work on the business for three years, with its first campaign breaking later this year.
Companies House currently stores and provides the information for more than two million limited companies in the UK.
It is responsible for ensuring that all registered companies provide the correct details required under the 2006 Companies Act, and for making sure that the information is easily accessible to the public.
At the same time, WDMP has also been appointed by ITN Source, one of the world's largest commercial providers of video footage, to handle its digital and direct marketing account.
The agency will create an on and offline campaign to drive content sales for the brand.
The work, which will break next month, will highlight ITN Source's ability to provide consumers with access to over one million hours of content from broadcasters including Reuters, ITN, ITV Productions and Fox News.
ITN Source provides archive footage dating back to 1896, and covers a range of genres including news, comedy, music, wildlife, natural history and film.