Markle's engagement ring features diamonds from Diana's collection.
The engagement was publicly announced today (Monday) with the wedding set to be held in spring 2018.
The wedding of Prince Harry and Meghan Markle will not be a national holiday, Downing Street has announced.
Thirty-six-year-old Meghan Markle has always been consistent with her impeccable sense of style, and she did not disappoint when she made her first public appearance as Prince Harry's fiancée.
And it was an instant "yes" from Ms Markle.
He tweeted: "Congratulations to my TV daughter Meghan Markle and Prince Harry on the news of their wedding engagement. But we're happy. Personally, I love a great love story", she continued, referencing their choice to keep private.
After their engagement, Harry informed the queen, close members of the royal family and also sought the blessing of Markle's parents.
"The fact that I fell in love with Meghan so incredibly quickly was confirmation to me that all the stars were aligned, everything was just flawless", Harry said.
SC women's hoops coach: No White House invite
Some teams have already made the trip to Washington. "We'll go to the White House", she said at the time. SC won the 2017 Women's NCAA Tournament, but isn't going to the White House.
The Queen and Duke of Edinburgh said they were "delighted for the couple and wish them every happiness", a Buckingham Palace spokesman said.
"At the end of day I'm really just proud of who I am and where I come from and we have never put any focus on that", she said.
It described nightly legal battles to keep defamatory stories out of papers, attempts by reporters and photographers to get into her home and the "bombardment" of almost every friend and loved one in her life. "We were just hit so hard at the beginning with a lot of mistruths".
Exasperated by the media frenzy, the palace also released an extraordinary statement attacking the "sexism" and "racism" directed at Markle, who is of mixed race.
Markle, who has a starring role in the Toronto-filmed U.S. TV show "Suits", has lived in the Canadian city for several years. She was born and raised in Los Angeles and graduated from Northwestern in 2003.
There is a long-running custom barring royals from marrying Catholics and divorcees.
Markle spoke to Vanity Fair in September about being "in love" with the Prince.
Like Prince William's wife, Ms Markle will not become a princess in her own right after the marriage.
It has also incorporated two smaller diamonds from Princess Diana's collection, "to make sure that she's with us on this insane journey together".