The royal, who is William's cousin, told Orange Is The New Black star Uzo Aduba how thrilled she is that the couple will welcome a new baby next year, adding that the she had "much to celebrate" on the night she found out the news.
Eugenie and Uzo were deep in conversation at the US Open on Tuesday, which the Princess attended with entrepreneur Phil Winser.
Princess Eugenie is "excited" for pregnant Kate
The following day Eugenie and her mother Sarah Ferguson made a joint appearance at BGC's Charity Day in New York, their happiness at the family's news evident in their broad smiles.
Princess Beatrice hits the trading floor to support Mark Shand's wildlife charity
In the wake of the surprise announcement that Kate is pregnant, numerous royals have spoken of their joy for the couple.
Eugenie made the comments at the US Open on Tuesday
The day after Clarence House confirmed William and Kate are expecting baby number two, Prince Charles announced that he was "thrilled" for his son and daughter-in-law.
Duchess Kate 'wants at least three children'
"It's wonderful to have another one," said the first-in-line to the throne. "I'm happy I'm going to be a grandfather again. I'm looking forward to it – but I hope it will be a girl this time."
Prince Harry has also expressed his enthusiasm at having a new niece or nephew, saying that he thinks Prince George "will be thrilled having another small younger brother or sister."
Harry also joked that he is keen to see his brother William "suffer more", with the arrival of the new baby.