The agreement will see channels ITV1 and ITV Play – an interactive gaming channel – available to 3.5 million customers.
ITV1 will be the first terrestrial channel to be streamed to mobile phones.
Mobile TV viewing is complementary to traditional viewing, according to 3, with people catching up on missed episodes while travelling or away from a TV set.
Charles Allen, chief executive of ITV, said the deal would make "fully streamed mobile TV a reality".
"Today is a real milestone in the development of TV on the go and with ITV’s new broadband channel coming soon, viewers will be able to access ITV's great content wherever, whenever, and however they choose," Allen added.
Bob Fuller, chief executive of 3, commented that the partnership provided an "exciting prospect for broadcasters, advertisers and audiences."
"It offers the first true mainstream experience of mobile television and adds a new dimension to the traditional way our customers watch television," Fuller said.
The exclusive licence with ITV will run for six months initially. In terms of coverage, the channels will be available to 89 per cent of the UK population.
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