The couple would take wedding vows at St George's Chapel in Windsor around mid-day. The Duke of Cambridge, Prince William, will be seen alongside Prince Harry as his Best Man. Around 600 people have been invited to the service.
After the service, around 1 pm, Meghan Markle and Prince Harry will travel around Windsor in a horse-drawn carriage where people will be able to see them and join the royal wedding celebrations.
Prince Harry and Ms Markle have also invited 2,640 people into the grounds of Windsor Castle to watch the arrivals of the bride and groom.
After this, there will be a reception at St George's Hall, which is being given by Queen Elizabeth II.
Later that evening, the Prince of Wales will give a private evening reception for the couple and their close friends and family.
A lemon elderflower wedding cake will be created by American pastry chef Claire Ptak.
Floral designer Philippa Craddock will create floral displays in St George's Chapel which will be created using locally sourced foliage, much of which will be taken from the gardens and parkland of The Crown Estate and Windsor Great Park. After the wedding, the flowers will be distributed to charitable organisations.