Sir Paul McCartney is among the big names who have signed up for a TV concert to support health workers fighting the coronavirus.
One World: Together at Home will be live-streamed in the US on 18 April and screened on BBC One the following day.
Others performing include James Bond theme tune winner Billie Eilish, Stevie Wonder and Sir Elton John.
The event will support the COVID-19 Response Fund, powered by the UN Foundation, in the global fight against the disease.
Lady Gaga has already raised £28 million with Global Citizen to buy protective equipment for health workers and support efforts to develop drugs and vaccines.
She said she wanted to stress “deep gratitude” felt towards the medical community who are fighting the coronavirus pandemic.
“My heart is very achy and warm for those who are ER doctors as well as nurses who are sleeping in cars to make sure they don’t infect their families or their patients,” said the singer, whose real name is Stefani Germanotta.
“What you are doing is putting yourself in harm’s way to help the world and we all salute you.”
The TV concert will be hosted by US talk show hosts Jimmy Fallon, Jimmy Kimmel and Stephen Colbert. It will also be streamed on social media platforms.
Other artists appearing include Alanis Morissette, Andrea Bocelli, Chris Martin and David Beckham.
In line with social distancing guidelines, performers will appear remotely. Full details of the logistics will be announced in due course.
Lorna Clarke, controller BBC Pop, said: “I’m thrilled that BBC One is to broadcast coverage of this very special event, featuring some of the world’s most loved musicians, to show support to care workers all over the world at this challenging time.”
Lady GaGa has made clear that One World was not a fundraising telethon and would focus on entertainment and messages of solidarity.
“Put your wallets away… and sit back and enjoy the show you all deserve,” said the singer.
A number celebrities have been raising funds to help the health emergency.
Angelia Jolie, Rihanna, Taylor Swift and Ryan Reynolds have donated money to organisations and individuals affected by Covid-19.
Former Beautiful South singers Paul Heaton and Jacqui Abbot will play a free show in October for NHS staff.
Liam Gallagher has even floated the idea of a one-off Oasis reunion in aid of frontline workers.
He wrote a message on Twitter clearly aimed at brother and former bandmate Noel: “Sick of pleading, begging, etc. I demand an Oasis reunion after this is all over, all money going to NHS. C’mon, you know.”
Italian tenor Andrea Bocelli will give a solo performance at the Duomo di Milano, the cathedral of Milan on Easter Sunday. It will be streamed on his YouTube channel.
On 23 April, the BBC will broadcast its own Covid-19 morale booster and fundraiser called The Big Night In.
The show is being put on in partnership with the BBC’s charitable partners Children in Need and Comic Relief but the names of those taking part have not been announced.