The pair looked happier than ever on the outing at St Mary Magdalene Church on the monarch's Sandringham Estate in Norfolk. And is wasn't hard to guess why – the couple were celebrating their first Christmas as a family of three with their five-month-old, Prince George.
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Although they left the little Prince at home, he was the main topic of conversation when the couple spoke to well-wishers at the church.
William told crowd: "We've had a good morning with George and I can't wait until next year when he's bigger."
Kate was as elegant as ever in a plaid Alexander McQueen coat and green fascinator by Gina Foster during the couple's return to the service this year after giving it a miss in 2012.
Last year the brunette royal was still in the early stages of pregnancy and recovering from a bout of servere morning sickness, so instead the couple spent the day with Kate's parents Michael and Carole Middleton at their mansion in Bucklebury, Berkshire.
Also back this year for the largest Christmas family gathering in recent years was Prince Harry – who in December 2012 was on the front line in Afghanistan as an Apache helicopter pilot.
Meanwhile attending her last Christmas day service before welcoming her own baby was Zara Phillips. Princess Anne's daughter, who is in her eighth month of pregnancy, looked delighted to be with husband Mike Tindall and her nearest and dearest.
Other royals joining the group included Zara's brother Peter Phillips and his wife Autumn, The Earl and Countess of Wessex and their daughter Lady Louise, and Prince Charles and the Duchess of Cornwall.
Prince Andrew also attended with daughters Princess Beatrice and Princess Eugenie, who is back from New York, where she has just started a new job working for an auction house.
After leaving St Mary Magdalene Church, which is just a short walk away from Sandringham House, the royal family enjoyed a lunch of Norfolk turkey. They then settled down to watch the Queen's speech. In line with tradition, presents were opened on Christmas Eve.