The siblings smiled for the adorable photograph, both with their hair tied up in matching yellow scrunchies.
“#tbt to cheeky smiles and scrunchies with my sister,” Princess Eugenie captioned her heartwarming post.
As expected, followers have been very quick to share their well wishes with the royal duo.
“Aww such a pair of cuties!!,” commented one, whilst another added: “Beautiful girls 💕 ”
“You both have not changed! Little Princesses 💕,” a third posted.
Beatrice appeared to go public with her new boyfriend, Edoardo Mapelli Mozzi, in New York on Thursday.
Attending a glitzy party together, the duo appeared to confirm their romance – with the princess reportedly sparking up a romance with the property developer back in early October.
However, the couple decided to opt out of any photographs together – leaving an air of mystery to their possible romance.
Prior to meeting Edoardo, Princess Beatrice was in a 10-year relationship with ex-boyfriend Dave Clark. The couple were initially introduced in 2006 before deciding it wasn’t meant to be and splitting mutually in 2016.
Princess Eugenie and Princess Beatrice are incredibly close, recently speaking with Vogue about their sisterly bond.
Princess Eugenie, who asked her 30-year-old sister to be the maid of honour at her royal wedding to Jack Brooksbank earlier in the year, revealed they rarely clash during the intimate chat.
“One of the biggest fights we ever had was about a pair of Converse trainers,” Eugenie explained.
“We have the same size feet and both of us had identical pairs. One pair got trashed and the other sister may have swapped them.”
They’re just like us!