James, Viscount Severn was spotted arriving at St Mary Magdalene Church in Sandringham.
Now aged 19 and 15, the two youngest grandchildren of the late monarch and Prince Philip have started to attend various royal events in recent months.
In September, James joined his sister and cousins at an emotional vigil for their late grandmother at her coffin.
At the vigil, James was seen wearing his Diamond and Platinum Jubilee medals.
Prince Edward, Earl of Wessex and James Viscount Severn attend the Christmas Day service
King Charles led the family on their walk to church
The commemorative medals were designed for the Queen’s Jubilee celebrations, and the late monarch, who gave them to members of the family.
The 15-year-old also made an appearance during Queen Elizabeth II’s Platinum Jubilee celebrations in June.
James, dressed in a smart suit, was spotted enjoying the entertainment at the Queen’s Jubilee concert.
James with his sister Lady Louise Windsor
Other royals joining the procession this morning include Prince and Princess of Wales and their children – Prince George, nine, Princess Charlotte, seven, and four-year-old Prince Louis, who walked hand in hand with Kate.
Members of the family were greeted outside the church by the Reverend Canon Dr Paul Rhys Williams before they climbed the steps to the church and the National Anthem was sung before the first hymn, O Come, All Ye Faithful.
Source: EXPRESS CO UK