Princess Charlotte can be seen in the centre of the picture pulling an amusing face, prompting smiles from the rest of the group.
The behind-the-scenes snap appears to have been taken in the White Drawing Room of Windsor Castle following the ceremony at St George’s Chapel on Friday.
Alongside the image, which also includes Prince George, Eugenie wrote: “Jack and I would like to thank everyone who was involved in making our day so special and for all the wonderful wishes as we start married life laughing together."
The 28-year-old princess, who is ninth in line to the throne, is beaming in the picture in her wedding dress designed by Peter Pilotto and Christopher De Vos.
Prince Harry and Meghan Markle used the occasion to inform the royal family they were expecting a baby , which sparked suggestions they had overshadowed the newlyweds on their big day.
The Duke and Duchess of Sussex had held their own wedding at the same chapel five months previously.
Mr Brooksbank, 32, a drinks executive who was previously manager of the Mayfair nightclub Mahiki, has been the princess’s boyfriend since they met in the Swiss ski resort of Verbier nearly eight years ago.
Most senior royals were there to support the couple including The Queen and the bride’s uncle, The Prince of Wales, as well as the Duke and Duchess of Cambridge.
A heavily pregnant Pippa Middleton arrived with her husband James Matthews, and she has since given birth to a boy.