Markle is a self-described feminist who has hinted she has found her match with Prince Harry.
Markle, 36, a California native who was married once before, will follow centuries of British royal tradition by reciting vows written by the Church of England.
In those vows, used by Queen Elizabeth in 1947, the groom promises "to love and cherish till death do us part" and the bride promises to "love, cherish and obey."
In the modern vows, from the Common Worship book, introduced in 2000, the word "obey" is excluded:
"I, (bride/groom name), take you, (groom/bride name) to be my wife/husband, to have and to hold from this day forward; for better, for worse, for richer, for poorer, in sickness and in health, to love and to cherish, till death us do part."
Markle is now a member of the Church of England after being baptized and confirmed in March by the Archbishop of Canterbury Justin Welby.
Welby was selected to perform the ceremony due to the “close bond” he has developed with Markle, guiding her on the sacraments of the Church of England.
Markle was raised Episcopalian but attended a Catholic high school in Los Angeles. She was not required to be baptized before her marriage to Harry but Kensington Palace announced she would do so after their engagement was announced last November.
Markle's advocacy for women
While making a name for herself as an actress, Markle worked on women's rights issues with organizations including World Vision, the Myna Mahila Foundation and One Young World.
She delivered a powerful speech on women's rights before leaders of the United Nations in 2015.
"It isn’t enough to simply talk about equality. One must believe in it," she said. "And it isn’t enough to simply believe in it. One must work at it. Let us work at it, together, starting now."
Markle may also stand out on her own on her wedding day by giving a speech at her own reception to thank her friends and family and to pay tribute to Harry and his family. She could have a chance to deliver two speeches.
Markle and Harry will celebrate their marriage at a reception at St George's Hall at Windsor Castle after the ceremony, as well as with an evening reception for close family and friends hosted by Prince Charles.