Head of press Donald Steel said the agency, which counts media firms Telewest, NTL and EMI among its regular clients, had been brought in to give strategic advice to the BBC's bid.
The licence is one remnant of the collapsed ITV Digital, for which the BBC is bidding in a consortium with BSkyB and platform technology supplier Crown Castle.
'Brunswick is able to give us advice on the business side because it has experience of this type of bid,' Steel said. 'The PR department here is primarily for programme publicity and reactive work and we needed extra help.'
The Brunswick team, which was hired when the BBC confirmed it was planning a DTT bid two weeks ago, is headed by partner James Hogan and senior associate Craig Breheny.
Hogan, who heads the agency's telecoms, media and technology practice, confirmed the appointment.