The couple’s first child is due early next year. The Queen, Prince Philip, Sarah Ferguson, Prince Andrew and Mr Brooksbank’s parents are said to be “delighted”.
The palace said in a statement: “Her Royal Highness Princess Eugenie and Mr Jack Brooksbank are very pleased to announce that they are expecting a baby in early 2021.
“The Duke of York and Sarah, Duchess of York, Mr and Mrs George Brooksbank, The Queen and The Duke of Edinburgh are delighted with the news.”
Eugenie took to Instagram to reveal she and Mr Brooksbank are “excited” for 2021.
She shared a picture of an adorable pair of baby shoes and a snap of the couple grinning.
Eugenie wrote: “Jack and I are so excited for early 2021….”
Royal fans were quick to congratulate Eugenie and Mr Brooksbank on social media.
One Twitter user wrote: ”Oh, what fabulous news! Congratulations to the happy couple!”
Another commented: “Congratulations, what lovely news! Wishing Princess Eugenie and Mr Brooksbank all the best.”
A third gushed: “Omg congratulations to them both! A new Royal baby!”
Another said: “Happy Days…..what fabulous news to receive over my morning coffee….
“Huge congratulations to both Jack and Eugenie, you have made my day. Good luck. Couldn’t happen to a lovelier couple.”
A fifth wrote: “Big congratulations to Her Royal Highness!!”
An Instagram user added: “Best news this year! Congratulations to both of you!!!”
The Queen’s granddaughter, who is tenth in line to the throne, and Mr Brooksbank tied the knot in October 2018.
They wed in front of 800 guests at St George’s Chapel on October 12.
The newlyweds took a carriage ride through Windsor after the spectacular ceremony.
The Queen held an afternoon reception at Windsor Castle.
Evening celebrations took place at the Duke and Duchess of York’s Royal Lodge residence.
Eugenie and Mr Brooksbank’s royal baby is the first since Meghan Markle and Prince Harry’s son Archie was born in May 2019.
The tot will be the Queen’s ninth great-grandchild.