The founder of 20:20, Peter Riley, will become chief creative officer of a new division within DMG, also to be called 20:20.
The division will house 20:20 London and DMG's existing digital marketing agencies, which will be rebranded early next year under the 20:20 name though their management will still report to the DMG board.
InboxDMG, GraphicoDMG, HyperLaunchDMG will be collectively renamed as the 20:20 Network, offering web design and build, online marketing and advertising, e-CRM, viral marketing, social media and online PR.
The division's lead digital and mobile creative agency will be 20:20 London.
CyberDMG becomes 20:20 Technology, offering e-commerce and systems integration.
CheezeDMG and the multichannel marketing analytics business of JaywingDMG become 20:20 MediaAnalytics, offering PPC skills and data analytics.
DMG's other agencies, which focus on data-driven marketing services, will also remain unchanged managerially and continue to operate under the DMG brand.
Ben Langdon, the chief executive of Digital Marketing Group, praised digital agency's credentials.
Langdon said: "20:20 leads the way, both creatively and strategically, in the digital and mobile space and, in Peter Riley, we have found the creative talent and creative leadership that our business deserves."
Founded in 2003, 20:20 London has worked with clients including BP, EA Sports, Red Bull, Lotus and Procter & Gamble. It has won several awards including two Cannes Gold Lions in 2006 for its work for PlayStation game '24'.
However, the agency's financial performance has not been strong of recent times. In the year to 30 April 2009 it reported earnings before interest, taxes, depreciation and amortisation of £270,000.
The deal is structured with an initial payment of £1.5m in cash and a further £250,000 in DMG shares on completion. After three years a performance-related sum of up to £250,000 in DMG shares will be paid.
Riley said: "We have the opportunity to grow the 20:20 brand into the biggest and best name in digital marketing in the UK, which is a challenge I look forward to."