Her Royal Highness has organised her customary Yuletide celebration at the historic Abbey, with attendees featuring royals, celebrities and local heroes who have made a difference in their neighbourhoods.
The large audience will hear a blend of carols, music and readings from performers including award-winning actors.
The theme of the concert, held in the candle-lit Abbey on Friday, is kindness and showing love to others.
Attending the event are a couple named the Cordiners, whose child passed away from a tumour, and who set up a charity, Kayleigh's Wee Stars, to help households where there is a terminally ill child.
"The dedication, empathy, and kindness you show, often discreetly and without words, and without any hope for reward or acknowledgement, make an remarkable change to the well-being of people," the Princess expressed in a message before the festive gathering.
The Princess of Wales is continuing her own measured re-emergence to the public eye subsequent to her illness and medical care, in November making her initial major address in two years, in which she discussed recognising the "discreet, frequently unseen labour of caregivers".
Those coming to the Abbey can listen to young musicians supported by the Future Talent organisation, set up with the help of the late Duchess of Kent to increase availability of music lessons.
Carys Wood, aged 18, who plays the trumpet and is from southwest Wales, has been supported by the trust, with grants helping towards musical instruments, lessons and travel costs - and she said it was "incredible" to be taking part in the evening's event.
"Music can be very expensive," Carys said. She is now studying at the Royal Academy of Music, and added that "all people deserve the chance" to develop their musical skills.
Carys's 11-year-old sister, Eliza, who is a euphonium player, will likewise attend the Abbey. "I never imagined I would perform in front of so many notable figures," she said.
Attending the service will be representatives of different generations.
That will include Saphia Turner, aged nine, winner of a young hero award, who sells artwork and carries out sponsored challenges to collect donations for local food charities.
The Abbey has been adorned with handcrafted festive wreaths, with well-known chef Mary Berry and flower expert Simon Lycett helping to make them.
The musical lineup includes singer Katie Melua, choristers from Westminster Abbey and a Cornish sea shanty group, the group Fisherman's Friends, who said the opportunity to perform was "the perfect culmination."
The Together at Christmas carol concert will be broadcast on television on December 24th.
Lena is an environmental scientist and writer passionate about promoting sustainable practices through accessible, evidence-based content.