The 'Rock DJ' star has teamed up with the country singer on a track titled 'Collision of Worlds', which will feature as the end credits song for the film.
Paisley and Williams co-wrote the track, with the reinstated Take That star explaining: "It's an international kind of song that's inspired very much by the film - it wouldn't exist if it weren't for the story.
"Brad turned up with his guitar and a basic understanding of what he wanted the song to sound like. He played me a few chords and we noodled and twiddled our way into forming this song.
"It's back and forth colloquialisms between two different countries speaking the same language and not understanding each other - until now."
Williams is currently on the road with Take That on their record-breaking 'Progress' tour, with extra seats added to the Wembley Stadium dates going on sale earlier today.
The group are currently number one in the midweek album chart with their repackaged LP Progressed.
Cars 2 will be released in cinemas on July 22, while the film's soundtrack is available to download now.
Watch the teaser clip for Robbie Williams and Brad Paisley's 'Collision of Worlds' below: