Alcock joins from Disney-backed kids' TV broadcaster Jetix Europe, where he was senior vice-president of commercial affairs.
His remit will be to manage all commercial revenues across the business, as well as overseeing new business acquisitions and client retention.
He will also manage iCrossing's continued expansion into Europe following the firm's acquisition of German digital marketing agency 3GNet.
Prior to working at Jetix Europe, Alcock worked as head of commerce for interactive programming at BSkyB, where he was responsible for the launch of Sky's lucrative gambling platform Sky Bet.
Alcock has also worked at Flextech (now Virgin Media TV) where, as general manager of Screenshop, he launched the UK's first home shopping channel.
Alcock said that, in his new role, he would be looking at new platforms through which iCrossing could connect consumers to brands.
He said: "Search and social media are at the heart of what we do, but there are one or two opportunities around a new platform that we are particularly keen to develop."