The couple, who tied the knot less than five months ago on May 19th, arrived in Sydney on Monday morning for the Invictus Games.
The official announcement follows speculation that Markle, 37, was hiding a growing baby bump beneath her Givenchy coat at Princess Eugenie's wedding on October 12th.
"Their Royal Highnesses The Duke and Duchess of Sussex are very pleased to announce that The Duchess of Sussex is expecting a baby in the Spring of 2019," the announcement reads.
“Their Royal Highnesses have appreciated all of the support they have received from people around the world since their wedding in May and are delighted to be able to share this happy news with the public.”
“Of course,” Harry said when asked about baby plans during an interview with the BBC after the pair got engaged. “You know, one step at a time. Hopefully we’ll start a family in the near future.”
The pair began dating in July 2016 after meeting on a blind date and were first revealed as a couple in October 2016.