The royal baby, whose name has not yet been revealed, will now sit in 11th place on the line of succession, one place behind Eugenie and their extended family members.
As a result, the Queen’s youngest child, Prince Edward, will be shifted from 11th to 12th place.
Eugenie and Jack first shared the news they were expecting back in September, when the palace released an official statement confirming the pregnancy.
"Her Royal Highness Princess Eugenie and Mr Jack Brooksbank are very pleased to announce that they are expecting a baby in early 2021," the statement read.
"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," the official statement said at the time.
At the time, Eugenie also shared her own personal announcement on her social channels.
In two adorable snaps, the princess shared a photo of herself and husband Jack, plus a close-up of their hands holding a pair of adorable fluffy baby shoes.
"Jack and I are so excited for early 2021...." Eugenie captioned the photos.
Royal author Phil Dampier said: "It will be tremendous news for the royals if Eugenie is pregnant."
"The Queen and Prince Philip will be delighted to have yet another great grandchild and it would be the perfect present next year for Philip's 100th birthday."
"It's been a rotten year for Eugenie what with the Epstein scandal engulfing her father Prince Andrew so this is the best tonic for the whole family."
"For once, it will take the headlines away from Andrew and his association with Jeffrey Epstein,” the royal commentator said.
After eight years of dating, Princess Eugenie and Jack tied the knot in a lavish ceremony at Windsor Castle in October 2018.
A huge congrats to the Yorks on their beautiful bundle!