The 'Enter Sandman' rockers will top the bill at the dual-sited event for the fourth time next August and are beyond thrilled to have landed the gig, reported BBC online.
Drummer Lars Ulrich said, "We are obviously beyond thrilled to be returning to headline the magnificent and mighty double shot at Reading and Leeds for the fourth time. We are practically the house band. Bring it!"
Event organisers are delighted to have landed Metallica - who headlined Glastonbury earlier this year - and think they will give an 'amazing' performance.
The festivals take place over the weekend of August 28-30 and tickets are on sale now.