Also on her left ring finger was her wedding band, a simple gold ring paired with her sapphire engagement ring.
It's unknown where the newlyweds honeymooned, but Eugenie looked incredibly happy and refreshed.
Eugenie's older sister Princess Beatrice was also in attendance at the party.
Earlier in the evening she had attended a star-studded Global Gift Gala, where she was photographed alongside Victoria Beckham and Eva Longoria.
30-year-old Beatrice stunned in a floor-length Gucci gown.
She got into the Day of the Dead theme by wearing a fun and colourful garland headband later in the evening.