Her Royal Highness has organised her yearly festive musical service at the iconic London venue, with attendees featuring dignitaries, stars, and everyday helpers who have supported their local areas.
The 1,600 guests will enjoy a blend of carols, music and readings from performers including Kate Winslet and Chiwetel Ejiofor.
The central message of the event, held in the candle-lit Abbey on Friday afternoon, is compassion and demonstrating care for others.
In the audience are Jonathan and Anna Cordiner, whose daughter died of a tumour, and who set up a charity, a charity called Kayleigh's Wee Stars, to aid parents with a youngster facing a life-limiting condition.
"Your efforts, love, and understanding, often discreetly and without words, and without any thought of thanks or praise, make an extraordinary difference to the lives of others," wrote Catherine in a note prior to the carol service.
The princess has been making her own gradual return to the public eye subsequent to her illness and medical care, recently giving her major oration since 2023, in which she talked about recognising the "discreet, frequently unseen labour of caregivers".
Guests arriving at the Abbey will be entertained by young musicians supported by the charitable trust Future Talent, set up with the help of the Duchess of Kent to broaden opportunities for instrumental training.
Trumpeter Carys Wood, 18, who performs on the trumpet and is from southwest Wales, has been assisted by the organisation, with awards contributing to musical instruments, lessons and travel costs - and she said it was "amazing" to be playing at the concert.
"Pursuing music is often costly," Carys said. She is now a student at the prestigious music academy, and added that "everyone should have the opportunity" to cultivate their performance abilities.
Her younger sibling Eliza, aged 11, who performs on the brass instrument, will also be at the Abbey. "I never thought I'd be able to play there in front of so many notable figures," she said.
Attending the service will be individuals spanning multiple eras.
That will feature young Saphia Turner, nine, honouree of a young hero award, who sells artwork and carries out sponsored challenges to raise money for community pantries.
The Abbey has been festooned 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, the Westminster Abbey choristers and a maritime folk band from Cornwall, the Fisherman's Friends, who said the chance to take part was "a dream come true."
The festive event titled 'Together at Christmas' will be aired by ITV1 on Christmas Eve.
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