Alcock will be responsible for the delivery of commercial revenues across the business and will develop the commercial proposition for iCrossing in the UK.
In addition he will work closely with iCrossing in the US on the group's global commercial strategy and will manage new business acquisitions, as well as client retention and profitability.
Arjo Ghosh, chief executive officer of iCrossing, UK, said: "Mel's experience and knowledge in the media sector is second to none. He is passionate about our connected digital marketing approach.
"We expect to grow iCrossing's team with more appointments of Mel's calibre to ensure the continued strengthening of brands and engagement of consumers online for our clients."
At Jetix Europe, Alcock directed development and maintenance of all commercial revenues across the children's TV network. His wide managerial role took in all key areas, including advertising, digital, licensing, home entertainment, marketing, commercial research, programme development, channel distribution and strategic investments.
Alcock's media career spans 22 years and includes stints at BSkyB, where he was head of commerce for interactive programming. During his five years at Sky, Alcock was responsible for the development and launch of Sky Bet.
Prior to Sky, he worked for Flextech, now Virgin Media Television, as general manager of Screenshop.
Alcock said: "We want the iCrossing brand and business to set a new standard for digital marketing by building deeper, longer and more meaningful relationships with our clients.
"The company has matured rapidly into a full service digital marketing company, operating within a different competitive set more akin to traditional global advertising networks. I will be leveraging my skill sets and experience to help our existing clients leverage new digital opportunities and add additional world-class brands to our roster."