Cussen joins Google from Ning, the customised social network building business. He joined the company in 2009 as director of business development, based in Palo Alto, California.
He moved to London over a year ago to take up the role of vice-president and managing director of Ning Europe and Latin America, in charge of expansion, marketing, business development and localisation.
Prior to Ning, Cussen was director of content and marketing for Myspace.
Cussen will start in the newly created role next Monday (30 April) and will be based in Google's Central St Giles office in London. Google has not confirmed details of what his role entails or who he will be reporting to.
Cussen's appointment comes shortly after Google launched its first advertising push for Google+ in the UK, with a TV and digital campaign, which leverages storytelling to demonstrate the product.
The TV ad, created by Adam & Eve, broke on 31 March and introduced the strapline, 'That's the Plus'.
Google+ launched in June last year and now claims to have 100 million monthly active users and 50 million daily users.
Obi Felton, director of consumer marketing for Google EMEA, recently told Marketing that the Google+ was "often misunderstood" and was not a destination, but a "layer to the whole of Google to make it more social."
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