Iconmobile, which specialises in strategic planning, concept development and mobile design for content providers, is a Germany-based company founded in 2003. Its headquarters are in Berlin, with offices in Los Angeles, London, Sydney and Tokyo.
WPP said the acquisition was part of the strategic development of its networks in fast-growth markets.
The company, which has a client list that includes O2, Orange, Vodafone and France Telecom, has a number of associated firms, comprising icon impact, and IMT.
The group's consolidated revenues for 2006 were €6.6m (£4.5m), with gross assets at the date of acquisition totalling €6m.
WPP also acquired a 6.8% share in Media Rights Capital, the US content firm that specialises in film, TV, mobile and broadband services earlier in the week.