The band's new album Save Rock And Roll, which is due to be released on April 15/16, looks set to feature the two artists, although specific details of their involvement have yet to be revealed.
Asking fans to guess which blonde-haired singer who had also been nominated for a Golden Globe would feature on the album, the official Fall Out Boy Twitter account revealed: "It's Courtney, bitch."
Meanwhile, band member Patrick Stump tweeted an image of himself in a recording studio with Elton John with the caption: "#SaveRockAndRoll."
Fall Out Boy's new single 'My Songs Know What You Did In The Dark (Light Em Up)' is available to download now.
Watch the music video for 'My Songs Know What You Did In The Dark (Light Em Up)' below: