The announcement confirms that the couple had got engaged earlier this month and that the 33-year-old Harry had informed Queen Elizabeth II of his intention to marry Markle.
The couple will make an official engagement appearance on Monday afternoon before taking part in a broadcast interview which will air in the evening.
Clarence House issued a brief statement today that Prince Harry and Meghan Markle are set to marry in Spring 2018.
"When did I know she was the one?"
Ms Markle's parents, Thomas Markle and Doria Ragland, said their daughter was a "kind and loving person" and they were "incredibly happy".
"What I would also like to say is that I really do admire the way that Harry and his brother have drawn attention to mental health conditions all across the country".
"We wish them a lifetime of happiness and are very excited for their future together", the statement ended.
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"It has been wonderful getting to know Meghan and to see how happy she and Harry are together", the couple said in a joint statement.
The couple met in July 2016 in London, introduced by mutual friends, and the relationship was later confirmed by Harry's office following speculation in the press.
Markle is an actress who now stars on the television show "Suits". It's unlikely the Queen will attend as Markle is a divorcée and was previously married from 2011 until 2013.
Rumours of their relationship immediately set off a frenzy of media speculation and were confirmed when Kensington Palace issued an unprecedented statement in November past year condemning the "wave of abuse and harassment" directed at "his girlfriend".
Forgoing royal family history, Prince Harry may opt for a more intimate venue, unique to him and his fiancé. In recent months, they spoke publicly about their mother, Princess Diana, on the 20th anniversary of her death. Historically, Britain's royals have frowned upon such weddings but that changed as the Queen gave her consent in 2005 for Prince Charles to marry Camilla, Duchess of Cornwall, who was also a divorcee.
Additional details about the upcoming royal wedding, such as the date and location, will be released in due time.