BBC chairman Michael Grade is leaving the public broadcaster to become executive chairman of ITV.
In a statement, ITV said Mr Grade would start in the role in early 2007. ITV had been without a boss since former chief executive Charles Allen said he would step down in August.
Mr Grade will succeed current ITV chairman Peter Burt with a view to staying for three years.
Within that time, Mr Grade and the board expect to appoint a chief executive with the 63-year-old Grade then stepping back from day-to-day management, to become non-executive chairman.
Mr Grade said it was a tough decision to leave the BBC but that it was an opportunity he could not resist. "My first priority at ITV will be to support the team in accelerating the improvement in programming performance for our viewers and advertisers," he said.
Analysts have described the move as a major coup for the ailing broadcaster, which has been losing audience and ad revenues in the face of tough competition from the Internet and digital channels.
Mr Grade joined the BBC in 2004 on a four-year contract and had been in the tricky job of negotiating with the government over increasing the licence fee.