Kensington Palace has also confirmed that the American actress’s mother, Doria Ragland, will be present at the ceremony.
It did not comment on whether any other members of Meghan’s family would be there.
Harry and Meghan are keen to “celebrate the memory” of Princess Diana, the palace said, in a major update on wedding arrangements.
Meghan will not be having a maid of honour, and the bridesmaids and page boys will all be children.
The Duchess of Cambridge will be taking Prince George and Princess Charlotte to the ceremony, but newborn Prince Louis will not be there.
It is hoped that Prince Philip, who is recovering from a hip operation, will be present.
Harry and Meghan will not be carrying out any more public engagements before the wedding, but will make a royal visit in the week after getting married.
They will not be going on honeymoon straight away.
Explaining that both of Meghan’s parents would have “important roles in the wedding”, the palace said that “on the morning of the wedding, Ms Ragland will travel with Ms Markle by car to Windsor Castle”.
The palace said it expected the journey to “take them along part of the Long Walk, allowing members of the public gathered there to see the car as it passes”.
It added that “Mr Markle will walk his daughter down the aisle of St George’s Chapel”.
There has been speculation over whether Meghan’s father, Thomas, would be performing the traditional role.
Some reports said Meghan was worried about how her dad, who is said to value his privacy, would handle the pressure.
Other reports said the 73-year-old was “excited” and looking forward to the big day.
The palace said Meghan was “delighted to have her parents by her side on this important and happy occasion”.
Ms Ragland, 61, a yoga teacher and social worker, and Mr Markle, a retired TV lighting director, divorced when Meghan was six.
Their arrival “in the week of the wedding” will allow “Prince Harry’s family, including The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, and The Duke and Duchess of Cambridge, to spend time with them before the big day”, the palace said.
Prince Harry is “keen to involve his mother’s family in his wedding”, it continued, adding that “all three siblings of Diana, Princess of Wales will be in attendance and Lady Jane Fellowes will give the reading”.
Harry and Meghan “both feel honoured that Lady Jane will be representing her family and helping to celebrate the memory of the late Princess on the wedding day”.
While the wedding will be “guided by tradition”, it will also reflect the “personalities of Prince Harry and Ms Markle”.
In the week before the ceremony, more details about the bridesmaids and page boys, the florist and the baker making the wedding cake will be released.
The full order of service will be published on the morning of the wedding.
Members of the Royal Family will begin to arrive at 11.20am, prior to the ceremony at midday.
Harry and his best man, Prince William, are likely to arrive by foot at the chapel’s west steps.
The palace said that would “allow Their Royal Highnesses to acknowledge all of the people gathered in the Castle precincts, including the 200 charity representatives gathered in the Horseshoe Cloister at the bottom of the steps”.
The service will take around an hour.
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Formal photographs, taken by Alexi Lubomirski, will be released the following week.
:: Sky News will broadcast live in Windsor the week before the royal wedding with all the build up to the big day, with exclusive live coverage of the wedding in UHD in a special programme from 9am to 3pm on Sky News and Sky One on Saturday 19 May.