MG OMD, which has an estimated 400 employees, is due to move into the 370,000-square-feet former Royal Bank of Scotland building in Southwark in December.
The move spells the end of a 20-year tenure in Marylebone for the shop, which was founded by Nick Manning and Colin Gottlieb as Manning Gottlieb Media in 1990. Omnicom bought the agency in 1998.
M2M will move to Bankside in October from its current office, which is also in Marylebone.
The two shops will join some of Omnicom’s biggest networks at the new complex, including Abbott Mead Vickers BBDO – whose creative staff rebelled against the building’s open-plan seating – and TBWA\London. Proximity London was the first agency to move into Bankside last year.
Until now, Rocket has been the only Omnicom media agency based in Bankside.
There are currently no plans for sister media agencies OMD UK and PHD to move to Bankside. Their adjoined offices are located near Tottenham Court Road.
Omnicom leased Bankside 2 and Bankside 3 from the Royal Bank of Scotland at the end of 2014. At the time of the deal, Omnicom was reported to be paying an average of £45 per square foot for the lease, putting its annual rent at £16.7m.
Tim Pearson, chief executive of MG OMD, said: "Our move gives us the opportunity to create a new environment that will enhance our creativity and collaboration."