The couple travelled there in a vehicle with blacked out windows and visited her private sitting room for an informal tea, The Daily Mail reports.
Now the meeting, which took place in the Queen's private sitting room on the first floor of the palace, has got royal watchers the world over excited about the prospect of another royal wedding.
That's the situation for Meghan Markle who-in case you've been living under a rock where there is no wi-fi-has been dating Prince Harry, with reports that things are headed towards marriage (and living together).
The brunette beauty looked to be keeping a low profile as she was spotted filming for the USA series, looking particularly glum as she returned to reprise her role as Rachel Zane in the popular show.
The meeting would make it the second time Meghan and her boyfriend's grandma have met, suggesting the pair are nearly certainly engaged. We're sure Harry's mother would be so proud of everything he's accomplished - especially his mature relationship with Meghan.
But before the games, Markle had given an interview to Vanity Fair, in which she spoke in a way that no other royal girlfriend or boyfriend had done so before.
It comes after the news that Markle, 36, quit her job on the television show Suits which some saw as preparation for a move to London to take up royal life.
Her character Rachel Zane has become a fan favourite. "I'm still the same person that I am, and I've never defined myself by my relationship". It's part of what makes it so special, that it's just ours.