The 60-year-old actress - whose weight has fluctuated over the years - showed off her newly-slim figure at The Studio at the Lincoln Center as she strutted her stuff for Malaysian designer Zang Toi.
Kirstie - whose blonde hair was pulled up into a large beehive-style bun - looked stunning in a blue gown and matching dress coat and she later donned a fitting black dress over a pair of leggings.
After the show, Kirstie tweeted: "Thank You all the REAL Models for letting me share @ZANGTOI runway with you!!!!! You all were sooo sweet and looked soooo gorgeous!!! (sic)"
She then added: "THANK YOU @ZANGTOI !!!! I love you!!! I had the time of my life!!!! (sic)"
Ricki Lake was one of the first celebrities to share their admiration for Kirstie, tweeting: "Wow! You are a goddess! Yes, indeed an inspiration to me!"
Other designers to have shown at NYFW yesterday, including Marchesa, Herve Leger, Oscar De La Renta and Tibi.