The 1939 song, which was originally performed by Lynn, 103, to boost morale during World War II, has seen a surge in streams since Queen Elizabeth II referenced it in her rare televised address to the British public and the wider Commonwealth amidst the coronavirus pandemic last week.
And so Lynn and the Welsh mezzo-soprano singer, 39, have decided to release the anthem on April 11, with all profits going to NHS Charities Together to support the healthcare workers working to help support and care for COVID-19 patients.
Lynn said: ''The words 'We'll meet again' speak to the hope we should all have during these troubling times''.
Katherine added: ''As Dame Vera herself has said, while the lyrics of 'We'll Meet Again' take us back to the time of WW2, the sentiment feels appropriate and meaningful today and relevant to the current crisis.
''It is a song of hope and Dame Vera and I sing this in honour of (and in aid of) our superhero NHS workers and their families.
''They are putting themselves at risk to ensure we will meet our dearest again.''
The pair previously performed the song at the 60th Anniversary of VE Day in 2005, and afterwards, Katherine was dubbed ''the new Forces Sweetheart'', a title held by Lynn.
The money raised from the duet will go directly to the 140 NHS charities in England, Scotland and Wales supporting frontline NHS staff and volunteers.
Spotify recorded that streams of 'We'll Meet Again' rose to more than 209 per cent week on week, following the British monarch's speech on April 5.
Donations can be made by visiting: uk.virginmoneygiving.com/charity-web/charity/finalCharityHomepage.action?charityId=1018947
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