The 52-year-old media mogul criticised the broadcaster at the press launch of his other show Britain's Got Talent, which will go head-to-head with The Voice on Saturday nights from this weekend.
Cowell said: "Of course I love talent shows, but if you ask the BBC, 'why do we need another singing talent show?', I would query whether you do or not. In my opinion they don't like the fact The X Factor's successful.
"They have every right to compete with us, but I have every right to arm ourselves so we're in a good place to beat them."
The BBC and ITV recently engaged in a scheduling battle, resulting in the first episodes of both shows - airing this Saturday - clashing for twenty minutes.
ITV had already brought Got Talent forward three weeks from its traditional mid-April launch, but it denied the move was motivated by The Voice.