Cowell recently confirmed that he will be leaving the Fox talent competition at the end of the current season to focus on bringing The X Factor to the US.
His departure sparked speculation that host Seacrest could step in as the fourth panellist. However, according to Entertainment Tonight, the reports are untrue.
A permanent replacement for Cowell has yet to be announced, although La Toya Jackson recently suggested that she is interested in securing the position, while producer Rodney Jerkins has also been linked to the role.
American Idol continues tonight on Fox.