Clarence House - the official residence of Prince Charles and his wife, Camilla, the Duchess of Cornwall - made the announcement in a letter early Monday morning.
The Prince of Wales is delighted to announce the engagement of Prince Harry to Ms. Meghan Markle. pic.twitter.com/zdaHR4mcY6— Clarence House (@ClarenceHouse) November 27, 2017
According to the official announcement, the couple got engaged in London earlier this month and their wedding will take place in the Spring of 2018.
It comes after weeks of speculation.
Harry's brother, Prince William, and his pregnant wife Kate welcomed Markle to the royal family.
"We are very excited for Harry and Meghan," they said in a statement. "It has been wonderful getting to know Meghan and to see how happy she and Harry are together."
The announcement means another grand royal wedding is in the offing - the first since William and and Kate married in 2011.
In some ways, Markle - a mixed-race American raised in California, an outspoken full-time actress, and a divorcee - makes a surprising addition to Britain's monarchy.
But the institution has moved on with the times, and the romance between Markle and Harry - who has repeatedly stressed his wish to lead as "normal" a life as he could - has a decidedly unstuffy, modern feel to it.
Markle, best known for her role as an ambitious paralegal in the hit U.S. legal drama "Suits," surprised many when she shared her feelings for Harry in a September cover story for Vanity Fair. Asked about the media frenzy surrounding their courtship, the 36-year-old said: "At the end of the day I think it's really simple ... we're two people who are really happy and in love."
Markle said she met Harry through friends in London in July 2016, and that they had been dating quietly for several months before the romance hit the headlines.
Harry and Markle held hands for their first official appearance together in September in Toronto at the Invictus Games, a sporting event for wounded service personnel that Harry spearheaded.
Harry - once known for his "bad boy" antics, including being photographed playing strip billiards in Las Vegas - has largely won over the British public with his winning smile, his military career and his devotion to charities aimed at helping disabled veterans and other causes.
The 33-year-old prince recently won praise with his work campaigning for more openness about mental health issues. Speaking candidly about his personal struggle to cope with the loss of his mother, Princess Diana, when he was only 12, he encouraged others to talk about their own problems rather than keeping them bottled up inside.