The short sleeve dress - which was custom made by Carolina Herrera - veers away from tradition, as the ladies of the royal family typically opt for long sleeve options at the annual Trooping the Colour.
Markle's sister-in-law, Kate Middleton, has always worn a sleeve past her elbow since she first made her Trooping debut in 2011.
The parade, which has marked the official birthday of the British Sovereign over 260 years, brings together over 1,400 parading soldiers, 200 horses and 400 musicians.