It's a party and Meghan Markle is invited.

On Wednesday afternoon, Dec. 20, Markle joined her future in-laws, Prince William and Princess Kate, at Queen Elizabeth II's Buckingham Palace for an annual pre-Christmas lunch.

The couple joined more than 50 family members who were present at the annual royal event. Some of the guests included Prince Charles, Camilla, Duchess of Cornwall, Princess Eugenie, Princess Beatrice, Zara, and Mike Tindal.

Meghan Markle Breaks Royal Tradition

Harry and Markle continue to break the royal tradition as reports indicate that the lunch should only be attended by only relatives and spouses.

The soon-to-be husband and wife arrived in a Land Rover Discovery, which was driven by Prince Harry. The Suits star wore a patterned outfit while Harry was dressed in a suit.

As expected, William and Middleton arrived together along with their children, Prince George and Princess Charlotte.

During the lunch, Markle mixed and mingled with several royals. Although Markle already met the Queen, this is the first time that the actress has met the entire family at the palace.

Every year, the Queen hosts a traditional lunch for her family before she leaves for her private Sandringham estate where she spends her winter break.

Last week, the Queen took Markle and Harry to a private party for staffers at Windsor Castle.

"It was a good opportunity for her to get to know the close part of the family as it were," a family friend said.

As reported earlier, Markle's holiday plans are official. The Suits alumna is set to join the royal family on Christmas Day at the Queen's Sandringham estate.

On Christmas Eve, the family will exchange gifts and then attend church at St. Mary Magdalene Church on Christmas.

In the couple's engagement interview, Markle touched on what it was like meeting Queen Elizabeth II.

"To be able to meet her through Harry's lens, not just with his honor and respect for her as Monarch, but with the love he has for her as his grandmother. She's an incredible woman," Markle said.

Markle's appearance at the annual Christmas lunch confirms that the actress has definitely been accepted into the monarchy.