However, while Meghan has never been one to conform to royal tradition, she was following in the footsteps of her late mother-in-law, Princess Diana.
The late Princess of Wales wore a strikingly similar tuxedo mini dress to her own charity event back in 1996.
The couple have a busy schedule in the coming days.
On September 4, Harry and Meghan for an annual awards night for his charity WellChild. The charity works on behalf of seriously ill children and their families and caretakers.
Two nights later, on September 6, the royal couple are slated to attend 100 Days to Peace, a gala evening of music marking the centenary of the end of World War I at Central Hall Westminster. The concert will benefit three charities that military veterans facing mental health challenges: Help for Heroes, Combat Stress and the Royal Foundation’s campaign on mental health, Heads Together.