Lund will be responsible for all of McCann Worldgroup’s UK agencies, including Weber Shandwick, MRM and Momentum.
Zaid Al-Zaidy, the chief executive of McCann London, will report to Lund.
In his new role, Lund will report to Luca Lindner, the president of McCann Worldgroup, and Harris Diamond, its chairman and chief executive. Diamond said: "We expect Mark to integrate the businesses much more than they already are. Clients want a marketing partner who can bring all these resources together. Given all the platforms, they want a single idea that can be exploited."
Diamond said he discussed the possibility of introducing the UK group chief executive role with Chris Macdonald last summer after the former McCann London chief executive moved to the New York office as its president.
Lund, who is leaving Now, the agency he co-founded in 2011, said that he did not yet know if changing McCann Worldgroup’s UK structure would be required.
He said: "My overall brief is to bring the businesses closer together and make them more effective in the way they work together, as they’re already effective as individuals."
Lund was previously the chief executive of COI and, before that, DLKW Lowe – another shop he co-founded.
Asked why he decided to join McCann, Lund said he had grown tired of running a start-up and had left Now in such a position that his job could be done by younger people.