The 4-year-old royal watched the celebrations along The Mall, which leads to Buckingham Palace, from the royal box with his siblings and parents, the Duke and Duchess of Cambridge.
Sitting beside his mom, Kate Middleton, Prince Louis went from sweet and cuddly to mischievous and sassy and back again many times over the course of day.
It was the perfect follow-up to his already-iconic scream at Thursday’s Trooping the Colour celebrations.
The pageant through central London featured the military, celebrities and thousands of volunteers, as part of the multi-day celebration of the queen’s 70-year reign.
The 96-year-old monarch appeared briefly on the Buckingham Palace balcony alongside her son Prince Charles and his wife, Camilla, the Duchess of Cornwall; Prince William and Kate, and their three children; Prince George; Princess Charlotte and Prince Louis.
Prince Harry, Meghan Markle and their two children, Archie and Lilibet, were also in the U.K. to celebrate the occasion but were not seen at Sunday’s festivities.
See some of the reactions to Prince Louis’ antics below.