Matrix Partners led the series B investment in the three year-old, London-based company, along with Eden Ventures and the company's Chairman, Charles McGregor.
Huddle, which "recently became cashflow positive," employs 40 in the United Kingdom and the United States. They anticipate quadrupling in size in the next year.
"Huddle has raised in excess of $15 million in equity funding since its launch in 2007. The company is using the capital to expand its U.S. presence and build a team in San Francisco led by its newly relocated co-founder, Andy McLoughlin."
Among the customers for their business social network offerings are Procter and Gamble, Disney, HTC, Panasonic, Kia Motors and Nokia; as well as governmental organizations like UNICEF and charitable groups.