The royals traditionally gather at the Queen's Sandringham Estate in Norfolk to enjoy the festivities.
Recent years have seen reduced numbers - last year the Duke and Duchess of Cambridge chose to spend Christmas Day with Kate's family in Berkshire, while Prince Harry was on tour in Afghanistan.
In 2011, Prince Philip was absent from many public appearances after being admitted to hospital for a heart operation.
This year there is expected to be a full complement as well-wishers gather to watch the royals make their way to the service at St Mary Magdalene Church on the estate.
It is possible Prince George will make a public appearance as his parents are expected the join the congregation.
There are unconfirmed reports that grandparents Michael and Carole Middleton could also attend.
Prince Harry is due to join his family after a short trip to Cape Town following his exertions in the Arctic with the charity Walking With the Wounded. It is not known if his girlfriend, Cressida Bonas, will be with him.
It is thought the royal habit of spending Christmas at Sandringham dates to Queen Victoria's reign.
The family traditionally open their presents on Christmas Eve and will enjoy a Norfolk turkey with all the trimmings after today's service.