Florence + The Machine is the third headliner confirmed for Barclaycard presents British Summer Time Hyde Park 2019.
It will be the singer's second headline performance at the festival, having previously played in 2016.
The National, Lykke Li, Khruangbin and Nadine Shah will also appear on the bill on Saturday, July 13. Tickets go on general sale on Friday (December 7).
Jim King, EVP live music, AEG Presents, said: "Over the past 10 years Florence Welch has rightfully cemented herself as one of the UK's finest performers. Her unforgettable live shows go from strength to strength with every passing tour. It’s a delight to welcome her back onto the Great Oak Stage at Barclaycard presents British Summer Time 2019 for what’s certain to be a phenomenal homecoming show.
"Joining Florence will be The National, another amazing band at the top of their game, as I’m sure anyone who saw them headline this years’ All Points East will agree. These two incredible artists will be joined by one of the strongest bills we have assembled for BST Hyde Park. It will be a magical day."
Bob Dylan and Neil Young have previously been announced as joint headliners on Friday, July 12, with Robbie Williams to close the 2019 event on Sunday, July 14.