The EMD superstar and the 'There's Nothing Holding Me Back' hitmaker will perform at Otterspool Promenade, Liverpool on September 1 and 2 respectively.
Whilst the Canadian pop hunk will be perform on the same day as Years & Years, James Arthur, Zara Larsson, Jax Jones and Louisa Johnson.
Shawn said: ''I'm so excited to be headlining Fusion this year. So many awesome musicians have played the festival in the past and I've heard it's incredible. Can't wait to see you all!''
Whilst 'I Would Like' singer Zara said: ''I love the UK and especially all of my fans over there so I can't wait to come back to perform at Fusion 2018!''
Damien Sanders, Event Director of Fusion Festival - which is once again sponsored by the Northern city's No1 Hit Music Station; Capital Liverpool - said: ''Every year Fusion grows and the line up is filled with more superstars. From Ed Sheeran to Little Mix and Take That to Ne-Yo, we never disappoint, and Fusion 2018 will once again impress the crowds with the biggest acts of the year playing including David Guetta and Shawn Mendes! We are delighted to be partnering with Capital Liverpool once more and can't wait to round off the summer with the biggest pop music event of the year!''
The stellar line-up follows on from last year, which saw the likes of Take That, Tinie Tempah, John Newman and regular Louisa Johnson wow the crowds at the seaside location in the North of England.
Tickets go on sale at 9am on Friday (23.02.18) at www.fusionfestival.co.uk
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