The happy couple were joined by a string of celebrities including Ellie Goulding, James Blunt and legendary Hollywood actor Robert De Niro.
Other guests included Beatrice’s mother Sarah Ferguson, the Duchess of York, sister Princess Eugenie, Kate Middleton's sister Pippa Middleton and her husband James.
The pair will reportedly wed in June after getting Her Majesty’s blessing.
A recent report claims the past few months have been tough on Bea and sister Princess Eugenie amid their father Prince Andrew's sex scandal.
Speaking at a charity event in London earlier this week, their mother Sarah 'Fergie' Ferguson said her daughters are the "most precious blood in my veins".
"Recently, you know... they are so strong and so steadfast. I believe we shine by helping others," she said.
"The girls are there, they're humble and they keep going on and on."