Recent reports claimed that Cowell and Spears had reached a "breakthrough" in talks and she was close to signing a $15m (£9.4m) deal to act as a judge on the talent show.
Speaking on Ryan Seacrest's KIIS-FM radio show, Cowell has now revealed that he would love Spears to appear on the show.
"If it was my decision, 100%," he said. "If we could get her, yeah."
When Seacrest's co-host Ellen K asked if he thought Spears would agree to appear on the show, he replied: "We'll have to find out very soon, darling... If we've spoken to her."
Cowell continued: "Don't forget, there's a lot of names that have been bandied around - some true, some false - but we've said to everyone we've spoken to we've got to keep quiet about it because you've got to wait until people sign up. But we're very, very close."
Former X Factor judge Nicole Scherzinger recently revealed that she is "rooting" for Spears.