The festivals, taking place over the August Bank Holiday Weekend, have been extended to include a Thursday event, with Kasabian headlining the inaugural slot.
Other artists announced for the lineup include Skepta, Jade, Kneecap, Geese, Sombr, and Role Model, with more acts to be revealed later.
Charli XCX's headline performance will be her only UK festival appearance in 2026, and Dave's shows are also exclusive to the festivals.
Tickets for the 2026 events go on general sale on Wednesday 3 December, following a presale that begins on Tuesday 2 December.