Thirteen will handle consumer PR for the 62-acre development, while Newgate will look after corporate comms.
Part of the remit will be to support attempts to encourage major global firms to locate to what its owners call London's "New East End", alongside start-ups from the creative, media and technology industries. There are plans to house "R&D hubs" for major brands and organisations.
Alongside some residential development, phase one of the project will see investment in the derelict Millennium Mills building, a former flour mill that occupies around 1,200,000 sq ft. In total around 2,500 houses are to be built and 14,000 jobs created.
Newgate and Thirteen, both part of global marcoms company Porta Group, are on an initial three-year retainer for the project, which is expected to take around 15 years to complete.
The contract was awarded by the Silvertown Partnership, a consortium of property developers First Base and Chelsfield, with funding from Macquarie Capital.
The account will be led by Andrew Baiden, chief executive of Thirteen Communications, and Deborah Saw, Newgate Communications managing partner.
Baiden said: "To work on a project that is breathing new life into a part of East London is such a rare opportunity and a major story to tell. The client has asked us to be as creative as the industry names who will be located here, so it is a wonderful canvas to work with."
He told PRWeek: "A lot of our communications are going to be with the local community, but also internationally, potentially through Newgate and Thirteen in our sister offices because we've got a global network."
The agencies will work alongside the London Communications Agency, which handles community comms.
The development area is located between the 'golden triangle' of the O2, Stratford and Canary Wharf, and London City Airport and owned by the Greater London Authority. "It's something that the mayor [Boris Johnson] is very much behind as part of his strategy for that part of London, and it's also part of the move of creative London to the east," said Baiden.
Saw said: "As London's original industrial heartland, the history attached to the Royal Docks mean this is a major platform for London's continued appeal to big brands, and the corporate and stakeholder audience will be interested in how Silvertown will be differentiated by communications. It really is a mouth-watering prospect to work on a project that will transform an area, creating a brand new district."