The high-society crowd were also enjoyed a sumptuous dinner hosted by Toujouri's director Lama El Moatassem, who created the company at the age of just 24.
Princess Beatrice with Amber Le Bon (left) and Alice Naylor-Leyland
While Beatrice opted for an all-black ensemble, Amber and Alice showed-off some of Toujouri's colourful evening dresses.
Princess Beatrice supports Mrs Alice in Her Palace at Fortnum & Mason
Alice, who is the founder of fashion blog Mrs Alice in Her Palace, turned heads in a sleek lilac dress with a matching embellished T-shirt over the top, while Amber, whose parents are Duran Duran musician Simon Le Bon and his model wife Yasmin, sported a vibrant cerise number.
Beatrice and Alice with Toujouri's director Lama El Moatassem
The preview, which was held at private members club The London Library, also played host to St Trinians actress Tamsin Egerton, style columnist Roxie Nafousi and model Sarah Ann Macklin.
Guests at the St James's Square venue were treated to a music performance by singer Georgia Buchanan.