The duo, who rarely pose for photos together, cuddled up for numerous pictures before heading on to Loulou's private members club to join Eugenie's mum Sarah, Duchess of York.
Eugenie, 24, sported a patterned black, white and blue dress and black heels for the evening while Jack looked dapper in a navy suit.
She was baptised in the Chapel Royal at St James's Palace on 20 December 1988, her godparents being: Viscount Linley (her father's cousin, now the 2nd Earl of Snowdon); the Duchess of Roxburghe (now Lady Jane Dawnay); Peter Palumbo; Gabrielle Greenall; and Carolyn Cotterell.
Beatrice began her early education at the independent Upton House School in Windsor, in 1991.
In 2015, she started working for the Hauser & Wirth art gallery in London as an associate director.