Markle sported a Stella McCartney cape dress in navy, which she matched to suede Manolo Blahnik pumps for a monochromatic look.
Standing alongside his bride-to-be, Prince Harry opted for a similar color palette and wore a blue suit with dark dress shoes.
Meanwhile, Queen Elizabeth II commanded attention in a shiny gold patterned dress, which she paired with low-heeled black shoes.
The queen’s birthday celebrations included a concert at the Royal Albert Hall in London with a star-studded lineup. Sting, Shaggy, Tom Jones and Kylie Minogue were among the performers who took the stage.
Markle and Prince Harry sat alongside the queen, joined by Prince Charles and Prince William. Kate Middleton, who is nine months pregnant with her third child, was not in attendance.
Markle may not be an official member of the British royal family just yet — she is set to wed Prince Harry May 19 — but she’s already filled her schedule with a slew of royal engagements.
Earlier today, she stepped out to a reception for the upcoming Invictus Games, hosted by the Australian prime minister, Malcolm Turnbull, and his wife. For the occasion, she looked spring-ready in a green floral-printed dress by Self-Portrait, which she paired with classic black pumps.