Nicky, 30, who is set to marry British banking heir James Rothschild, posted a picture of herself in front of the Eiffel Tower, gracefully displaying her glittering ring as touched her hair.
"#engagementmoon in Paris #FlashbackFriday," she captioned the image.
Previously Nicky's fans have only briefly seen her engagement ring she has been photographed going about her business in New York and despite getting engaged in August, the ring had not been on Nicky's hand in any of the pictures on her Instagram account.
Nicky's banker fiancé James popped the question when the lovebirds were on holiday, celebrating their anniversary with a road trip around Italy.
"They are both really excited and incredibly happy," a source told US Weekly. "He took her out on a boat into the middle of Lake Como and he proposed, got down on one knee and everything. It was incredibly romantic and beautiful."
Elder sister Paris, 33, was quick to congratulate the happy couple by captioning an Instagram photo of the pair with the message, "Congratulations @NickyHilton on your engagement! I'm so happy for you! You will be the most beautiful bride! Such a lovely couple! Love you both so much!"