He currently performs a similar role for the Interpublic network as the executive vice-president, director of strategic marketing technologies.
Blackden's task at Omnicom will be to develop and differentiate its digital product. He will also work with clients on identifying new areas for activity and attempt to increase margins across its digital business.
In addition, he will also work with senior digital staff at the OMG networks OMD and PHD on providing support and identifying which areas should receive group support.
Blackden, 41, has a strong background in digital media. He ran Zenith Interactive Solutions, the interactive arm of Zenith Media, before joining Universal McCann Interactive. He then spent two years as the joint chief executive of Universal McCann London, before moving back into a specialist digital role.
A key focus for OMG is to integrate its digital activity into the core of its media businesses to improve its ability to measure the effectiveness of work for clients.
Gottlieb said: "We're all going through a period of transition as the old model overlaps with the new one. I wanted an outstanding talent who could work directly with me across all our businesses to drive this transition. I know Damian will thrive in our environment."