"This wedding, like all weddings, will be a moment of fun and joy that will reflect the characters and values of the bride and groom."
The wedding, on May 19, will see the newlyweds make a carriage ride through Windsor town centre to allowed them to greet as many people as possible.
The 2,640 lucky invitees will be allowed inside the walls of the castle to watch the Prince and Ms Markle arrive at St George's Chapel: the first time the former American actress will be seen in her wedding dress.
Among them will be 100 pupils from two local schools, The Royal School and St George's School, both of which have a strong affiliation with the Windsor Castle community.
Another 200 people from a range of charities and organisations which Prince Harry and Ms. Markle have a close association with, including those which Prince Harry serves as Patron.
They are likely to include the stars and staff from the Invictus Games, veterans, mental health charities, HIV awareness campaigns and seriously ill children.
They may choose to invite representatives from homelessness charities, after controversial suggestions from a local councillor that beggars could be cleared from the streets for the wedding.
The largest group will be made up of 1,200 members of the public "from every corner of the United Kingdom", nominated by nine regional Lord Lieutenant offices.
"The couple has asked that the people chosen are from a broad range of backgrounds and ages, including young people who have shown strong leadership, and those who have served their communities," a spokesman said.
Roger Jones, interim headmaster of St George's School, Windsor Castle, said: "We are delighted and honoured that a number of our pupils will be a part of the royal wedding. It will be an incredible experience; one that will create memories that will live with these boys and girls for the rest of their lives.
"We will be working together over the coming weeks to decide which pupils will be in attendance."
Colin Dyer, chief executive of WellChild, which has had Prince Harry as its patron since 2007, said: "We are thrilled that WellChild and the families we support will be represented at the wedding of Prince Harry and Ms Markle.
"We are delighted, but not surprised, that they have decided that their wedding day is an occasion to be shared as widely as possible, supporting the organisations and issues which matter to them.
"We wish Prince Harry and Ms Markle a wonderful wedding day and married life together. We are very grateful that on their special day they have chosen to recognise among others, the work of WellChild, whose role as a critical lifeline to this growing population of children and young people is more important than ever."
The idea of inviting members of the public inside the ground of the castle sees the Prince and Ms Markle follow in the footsteps of the Earl and Countess of Wessex, who held a ballot system for their 1999 wedding.
As well as taking a carriage ride through Windsor town, Prince Edward and Sophie welcomed 8,000 lucky people, drawn by public ballot, to come closer to the action.
