As they walked into the Abbey’s forecourt, the royal children paused for a moment to post Christmas cards in a special post box containing messages for children who might be struggling this Christmas.
The sweet moment, reshared on TikTok by fan account @royal.tok, caught the attention of royal fans who couldn't help but notice Prince William's attentive and gentle parenting as he never let go of his youngest Louis' hands.
The father-of-three also regularly stroked his little boy's head, patting his on the back and even swapping which hand was holding onto Louis so that he could shake the Archbishop's hand without letting go of his son.
"William loves his children so much. He is such a good father," noted a royal fan, while another penned: "For a child, these situations can be overwhelming. William and Catherine show their children they are loved and important which is calming."
As Prince William guided Louis through the crowds, always making sure he had a gentle hand on the young Prince at all times, other royal fans made light of Louis' previous cheeky behaviour at major royal events.
MORE PRINCE LOUIS
"I would love to know what pep talk Louis got before this event," joked a viewer as another sweetly teased: "Those of us with 5-year-olds know this is so he doesn't escape."
Back in 2022, a then four-year-old Prince Louis dominated headlines during the late Queen Elizabeth II's Platinum Jubilee celebrations when he danced, laughed and roared his way through the Platinum Party at the Palace in the royal box.
The royal tot memorably blew raspberries at his mum, bounced onto King Charles' lap and even told off Princess Kate when she tried to calm his excitement.
Louis lived up to his riotous reputation during Trooping the Colour this year, when the playful young royal engaged in mischevious antics on the Buckingham Palace balcony with his royal siblings. Relive some of his best moments in the clip below...
The annual Together At Christmas concert, which is arranged by Princess Kate, brought together the likes of Princess Beatrice and Princess Eugenie, Zara and Mike Tindall, the Duchess of Edinburgh and more members of the Royal Family as they celebrated the occasion linked to the Princess of Wales' Shaping Us campaign.
The concert will air at 7:45pm on ITV1 and ITV X on Christmas Eve.
LISTEN: Don't miss the latest episode of HELLO!'s A Right Royal Podcast, where we go behind-the-scenes of The Crown with members of the crew.