George, Charlotte and Louis join Prince William, Princess Kate at Christmas carol service

Prince George, Princess Charlotte and Prince Louis got into the holiday spirit Friday, supporting their mom, Princess Kate, at her annual Christmas carol service at Westminster Abbey.

Charlotte, 8, wore a maroon coat dress that matched the maroon tie worn by her dad, Prince William, who was also in attendance.

George, 10, followed in his dad's footsteps by wearing a dark suit and tie, while Louis, 5, wore a dark pea coat and dark slacks.

Kate stood out in a cream pantsuit and coat as she hosted the "Royal Carols: Together at Christmas" program, which she first launched in 2021.

Each year, the program honors people who have "gone above and beyond to help others throughout the year," according to Kensington Palace.

This year, the program is spotlighting people who work in the early childhood space, which has long been a focus of Kate's royal work.

In addition to members of Britain's royal family, those attending the service include early childhood workers, volunteers from various charities, and people "who may have had a challenging year, including children and families," according to Kensington Palace.

Last year, Kate surprised audience members by recording a piano duet with Scottish singer-songwriter Tom Walker, who sang "For Those Who Can't Be Here."

This year's performers for "Together at Christmas," which will air on TV in the United Kingdom on Christmas Eve, include singer Adam Lambert and singer-songwriter and actress Beverley Knight.

Friday's carol service marks a time of unity for the royal family, which has faced controversy in recent weeks following the publication of author and royal reporter Omid Scobie's book, "Endgame."

In "Endgame: Inside the Royal Family and the Monarchy's Fight for Survival," Scobie, also an ABC News royal contributor, reports on an explosive claim made in 2021 by Prince Harry and his wife, Meghan, the Duchess of Sussex, that royals had conversations with Harry prior to the birth of Harry and Meghan's son, Archie, about their unborn baby's skin tone.

The Sussexes have never publicly stated the names of the royals they claimed discussed the topic.

Archie, who is now 4, was the first American British biracial royal born in the U.K., and is also widely considered to be the first mixed-race child born into the royal family.

When "Endgame" hit bookshelves in the Netherlands in late November, passages in the original Dutch translation of the book included two names of royals who were allegedly involved.

As a result, the book's Dutch publisher temporarily pulled its version of the book from shelves.

The two names cited in the book have since been publicly revealed in British press reports as Princess Kate, and the father of William and Harry, King Charles III.

A spokesperson for the Sussexes, who stepped down from their senior royal roles in 2020, has not responded to ABC News' request for comment about "Endgame." Members of the royal family have also not publicly commented on Scobie's book.

A Buckingham Palace spokesperson previously told ABC News that they were "considering all options" in the wake of Charles and Kate being named in reports by the British press.