Camila Cabello, Ed Sheeran and Snow Patrol will all play at next week's Concert For Ukraine, which will be broadcast on ITV and STV.
Emeli Sande and Gregory Porter have also been added to the line-up, with more acts to be confirmed.
Tickets for the show will go on sale on Tuesday 22 March, with the concert taking place in Birmingham on the 29th.
Cabello said her "heart was breaking" for the people of Ukraine, adding "we all have a responsibility" to help.
Proceeds from the concert will go to the Disasters Emergency Committee's Ukraine Humanitarian appeal, which is providing food, water, shelter and medical assistance to refugees in Ukraine and neighbouring countries.
ITV has also pledged that all sponsorship and advertising revenue generated from the broadcast - an estimated £3m - will be donated to the appeal.
"I will be singing to try to help every human being forced to flee their home and in solidarity with those being racially discriminated against even within this humanitarian crisis," said Sande in a statement.
"Nobody should be refused access to relief, aid and the right to cross the border to safety, and I'm pleased for the chance to support the DEC's appeal to help all people whose lives have been affected by the conflict."
Cabello added: "One of the biggest needs is to get funds to organisations who can serve these communities directly, so we're focusing our efforts on doing that as quickly as we can".
The show is being produced by ITV in conjunction with the Global radio network - which will broadcast live, behind-the-scenes coverage on its Heart and Capital stations.
London Calling repurposed
It comes as Russia's invasion of Ukraine enters its fourth week.
In that space of time, the United Nations' Office of the High Commissioner for Human Rights estimates the conflict has claimed 2,361 civilian casualties (902 killed and 1,459 injured). The UN also estimates that there are nearly 1.85million Ukrainians have been displaced.
The country's musicians have played a role in documenting the conflict and combating misinformation amongst their Russian fans.
Many of them - along with Russian musicians who oppose the war - have found themselves blacklisted by the Kremlin.
But that has not deterred hardcore punk band Beton, who have been given permission by The Clash to re-record London Calling as a protest song against the war.
Renamed Kyiv Calling, the song now includes the lyrics: "Kyiv calling to the Nato zone/Forget it, brother, we can't go it alone".
Recorded last week in Lviv, the video features footage captured by the band's family and friends of the attacks on Ukraine's cities.
Proceeds from the song will go towards the Free Ukraine Resistance Movement, helping to fund a shared communications system that will alert the population to threats and lobby for international support.
Discussing the track, Beton vocalist Andriy Zholob said: "Many Ukrainian musicians are now on battlefields or in territorial defence. This time they've changed guitars to guns. We hope this song shows Ukrainians' spirit and our defiance to Russian aggression."
The band are now also playing a part in the war effort. Zholob also works as an orthopaedic doctor, and is treating war victims and soldiers.
Drummer Bohdan Hrynko and bassist Oleg Hula have joined the territorial defence.