Pop star Dua Lipa and Panic! at the Disco will also perform, alongside BBC Music Sound of 2018 victor Sigrid.
What are your thoughts on the line up for Reading & Leeds so far?
Who's headlining Reading/ Leeds Festival? Many more acts to follow.More news: Judge closes courtroom as trial begins for Palestinian teen who slapped soldiers
Completing the quartet of headliners this year are Panic! at the Disco.
It's the world's oldest popular music festival and it's back again this year. Dance fans will have their fill with the likes of legends such as Annie Mac, Birmingham breakthrough DJ favourite Hannah Wants, Riton & Kah-Lo, Bristolian duo My Nu Leng and American genius and Major Lazer co-creator Diplo.
Tickets for Leeds Festival available here.
If something heavier is a little more your thing, UnderØath, Sum 41, Papa Roach, Waterparks, Hollywood Undead, Beartooth and Creeper are all in the mix.
It is fair to say Lamar is quickly becoming one of the most significant rap artists of all time, and in August festival-goers will be able to see him take the main slot for the first time.