Prince Philip and Camilla, Duchess of Cornwall, did not attend the service.
The unflattering stories have led some to dub Meghan "Duchess Difficult" because of how demanding she reportedly is.
Many had brought bouquets of flowers or had got in the Christmas spirit by wearing Santa hats.
But the "Fab Four" appeared as a united front as they greeted adoring crowds lined up outside the church in the English countryside.
There was no sign of the rumoured discord between Kate and Meghan as they and their husbands, Princes William and Harry, strolled to the traditional service at St Mary Magdalene church on the royal estate.
Last year, she became the first non-married partner to be invited to Christmas lunch at Sandringham with the Queen.
Afterwards the young royals went on a brief walkabout and when Meghan saw 17-year-old Jessica holding up a small sign with her Instagram username on it, Jessica Scarlett, she instantly recognised it and gave her social media friend a hug.
She said about the duchess, who closed down her social media accounts before her marriage to Harry: "This is the first time I've met her, she just said "it's so lovely to meet you, incredible to finally see you" and she was asking how we all are and if we're still talking and supporting each other".
Meghan Markle may now be gearing up for Christmas festivities with the royal family, but 20 years ago she was celebrating the holidays a bit differently.