The track, which serves as the theme song for Johnny English Reborn, was premiered on Soundcloud earlier today.
Lyrics on the track include: "When you're sleeping I watch you for hours/ Feels like reading or gazing at stars/ Never touching/ Just waiting for one to fall to earth and brighten up my empty words."
'I Believe In You' was written by Rumer and produced by Eg White, who has previously worked with James Morrison, Pink, Take That and Duffy.
The 'Aretha' singer's debut album Seasons of My Soul peaked at number three last November and has since sold over half a million copies in the UK.
The singer's biggest UK tour to date kicks off in Blackpool on November 10.
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Listen to 'I Believe In You' below: