ITV appointed BBH following informal talks that also involved incumbent HHCL and Partners. According to ITV head of marketing Jo Walker, who led the process, BBH was appointed because it impressed with its "creative insight, passion for the ITV brand and knowledge of all the different elements that go to make up the marketing of ITV".
The decision brings to an end the four-year relationship between the network centre and HHCL and Partners.
Walker paid tribute to the HHCL's work over the years and said it had put up a good fight to retain the business.
BBH will work alongside ITV's new marketing and commercial director Jim Hytner to create a more recognisable positioning for ITV1.
The agency's brief will go beyond merely creating ads, to providing consultancy on the marketing of ITV1 both on- and off-air.
The channel has struggled in the ratings war against a revitalised, well-resourced and highly competitive BBC One, which recently overtook ITV1's audience share for the first time since 1955.
ITV's £17m a year deal with BSkyB, making ITV1 and ITV2 available via the Sky Digital platform, is expected to boost viewing of both channels in Sky Digital homes.
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