A spokesperson for The Duke and Duchess of Sussex announced: "We can confirm that Archie is going to be a big brother. The Duke and Duchess of Sussex are overjoyed to be expecting their second child."
Her Majesty, the Duke of Edinburgh, Prince of Wales and the entire family are said to be "delighted" and to wish them well.
WATCH: Prince Harry and Meghan Markle announce second pregnancy
The announcement was accompanied by a gorgeous black-and-white photo of the pair showing Meghan with her head in Harry's lap as she cradles her baby bump.
The shot was that was taken remotely by photographer and friend of the couple Misan Harriman.
"With the tree of life behind them and the garden representing fertility, life and moving forward, they didn’t need any direction, because they are, and always have been, waltzing through life together as absolute soulmates," he commented on Sunday.
"To be asked to help share this absolute joy after such an unimaginable loss and heartache is a marker of true friendship," he added, referencing Meghan's sad miscarriage which she bravely wrote about at the end of last year. Talking to Vogue, he added: "Meg reminded me that had I not introduced her to a mutual friend then she wouldn’t have met Harry. I’m grateful for whatever small part I played."
The Duchess is wearing a long dress by Carolina Herrera, which she also wore during her pregnancy with Archie.
The couple released a gorgeous picture taken in their LA home
Sweetly, the news echoes Princess Diana's announcement of her pregnancy with Prince Harry, on Valentine's Day back in 1984.
The Queen and the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall, the Duke and Duchess of Cambridge and Meghan's mother Doria Ragland were all informed of news before the announcement.
"Her Majesty, Duke of Edinburgh, Prince of Wales and entire family ‘delighted’ and wish them well," a Buckingham Palace spokesperson confirmed.
The baby will be eighth-in-line to the throne when he or she is born, after brother Archie in seventh place and Harry in sixth.
Eugenie and husband Jack Brooksbank's first child, who was born earlier this week, will quickly move to twelfth place after Harry and Meghan's new baby is born.
The Duchess of Sussex is expected to give birth in a US hospital, given that she and the Duke moved to the States in March 2020, after their decision to step back from royal life.
The couple welcomed their son Archie in May 2019
Details around the birth have not been confirmed and Harry and Meghan are likely to keep them private, in line with the precedent they set with their first child Archie. The tot was born on 6 May 2019 at the private Portland Hospital in London.
Archie was christened in a private ceremony at Windsor Castle in July 2019, which was attended by the Prince of Wales and the Duchess of Cornwall, the Duke and Duchess of Cambridge, as well as Doria, who flew in from the United States.
The new baby is unlikely to be given a title like his or her big brother. Archie could have become Earl of Dumbarton – one of Harry's subsidiary titles – or he could have been Lord Archie Mountbatten-Windsor, but instead he is simply known as Master Archie Mountbatten-Windsor.
A source said at the time of his birth: "[Harry and Meghan] have chosen not to use a courtesy title."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.