He will leave the production company in March after ten years at the helm and is expected to launch his own production company in London this summer.
He will be replaced by Jonathan Davies, the former head of production at Leo Burnett Chicago.
Delaney, 39, joined the company from Spots Films in 1995 with a brief to launch a London office.
Delaney said: "The past ten years have been a great period for me and @radical.media. However, the time is ripe for me to move on and pursue exciting new opportunities that have recently arisen. I'm sure @radical.media will continue to enjoy the same success it has done for the past decade."
Under Delaney's management, @radical.media quickly rose to become a major force in UK commercials production and was shortlisted for Campaign Production Company of the Year within a year of its launch.
The company represents directors including Tarsem, Peter Darley-Miller, Sebastian Strasser and Greg Kohs. Recent credits for the UK office include ads for Carlsberg, Pepsi, Ikea and Vodafone.
Founded in 1994, @radical. media has offices in Los Angeles, New York, London, Paris, Berlin and Sydney.