The 34-year-old singer's new deal will double her fees from the last season on the same show, reported Daily Mirror.
She will be joining Gary Barlow, who will return as head judge on the show. Louis Walsh has already signed the deal to return for his tenth series and Sharon Osbourne is due to sign her deal in a few days time.
She will reportedly sign her deal this week.
"Simon knows how brilliant Nicole was last year and has to pay what she and her team feel she is worth," a source said.