The pair first made their name working with Naughty Boy, who signed them to his record label.
They went on to co-pen hits for the likes of including The Chainsmokers, Ella Henderson, Emeli Sandé and James Arthur, as well as joining the team at F Block, the music production studio based in Ealing Film Studios.
Mac & Phil said: ‘We started making music because of our undying desire to connect with everyone, and to one day have a big impact on the world, spreading love, peace and partying.
‘So it's an honour and a privilege to start our next chapter with such like-minded souls at Warner/Chappell; they are a company that truly value how important songwriters are and understand that ultimately, we're here to f**k shit up.’
Mike Smith, managing director of Warner/Chappell UK, added: ‘There is a new wave of young songwriters transforming music around the world right now and Mac & Phil are at the forefront of that.
‘They have written world class songs with Emile Sandé and The Chainsmokers and their ambition going forward knows no boundaries. They are an inspiration to work with.’
Hannan Malik, the pair’s manager at TenForty Management, said: ‘This is just the beginning for Mac & Phil and we're looking forward to embarking on this next chapter together with Warner/Chappell who have clearly put a lot of love and attention into songwriters over the last few years.
‘Mike, Tom and the rest of the UK team are fantastic. Their close working relationship with Katie Vinten and her team in LA was the icing on the cake.’