The composer made previous talent hunts How Do You Solve a Problem Like Maria?, Any Dream Will Do, I'd Do Anything and Over the Rainbow with the BBC and it was initially suggested that the broadcaster had passed on the new programme.
"The people at ITV now were the same ones who took a gamble on me in the first place at the BBC, so that's why I have moved over," Lloyd Webber told the Daily Mail.
"ITV wanted very much to do a programme with me. They got very excited when I said, 'I don't really want to do another stage show, I'm thinking of an arena tour of Jesus Christ Superstar'. They said that was something they would really like to do, too."
BBC presenter Graham Norton said in 2010 that while it was "sad" that Lloyd Webber would not be making new shows with the broadcaster, he would not be "mourning" or "lying in darkened rooms".
Defending the format, Lloyd Webber pointed to 2008's third-placed I'd Do Anything contestant Samantha Barks, who has been cast as Eponine in the upcoming movie adaptation of Les Misérables.
"She was a 17-year-old girl I would never have seen in my life if it wasn't for TV," he said.
"Now she's bagged a huge role in a huge movie. There are a lot of people who now apply just to get an audition with me and the team because they have seen the consequences of just being on the show."
Superstar starts tomorrow (July 7) at 7.25pm on ITV1.
Andrew Lloyd Webber's 'Superstar' auditions - photo gallery: