The 43-year-old is to front ITV's football coverage and will also be a main anchor on GMTV, which is currently undergoing a major revamp.
In a statement, Chiles confirmed that he is "absolutely delighted" with his new deal, which will see him presenting World Cup, Champions' League and England matches.
He said: "The chance to front ITV's football coverage and GMTV would have proved an irresistible opportunity at the best of times. But, coming as it did at an awkward period for me at the BBC, it made the decision not quite as hard as it might have been."
The star added that it was "no secret" he was disappointed over plans to replace him with Chris Evans on Friday editions of BBC evening programme The One Show, which he has fronted since 2006.
He explained: "I would have been happy to stay at the BBC doing the same shows on the same terms, especially The One Show, of which I am so proud having worked on it since the first pilots four years ago."
A BBC spokesman said: "We would like to thank Adrian for his contributions to his programmes and we wish him well for the future."
Strictly Come Dancing winner Chris Hollins is expected to take over from Chiles on The One Show, BBC News reports. Replacements for his other shows Match Of The Day 2 and The Apprentice: You're Fired! are likely to be announced in due course.