Family and friends of the couple were met by the subtle scent of fresh flowers as they entered the Gothic chapel through doors adorned with a floral arch of luscious green foliage and white blooms.
Before the wedding got under way, the atmosphere inside the Chapel was jolly, with the anticipation building, and it feeling more like a garden party than a solemn religious occasion.
Hollywood star George Clooney and his lawyer wife Amal Clooney, US talk show host Oprah Winfrey, British actor Idris Elba, tennis champion Serena Williams and Meghan's former cast mates from Suits were among the famous faces at the wedding.
Other big names taking their seats were David and Victoria Beckham, and singer James Blunt. Former prime minister Sir John Major and his wife Dame Norma were also in attendance.
Guests milled around before the service began, and David Beckham could be seen chatting to James Middleton, the brother of Kate - Duchess of Cambridge - in the chapel.
Victoria stood and chatted with Carole Middleton and Pippa Matthews, Kate's mother and sister.
Once seated, the Beckhams chatted with the couple next to them in the Nave area.
The couple were also spotted sharing a joke with Sir Elton John and David Furnish.
The Beckhams were at the wedding of Kate and William in 2011.
Harry, looking dapper in his frockcoat uniform of the Blues and Royals, walked up towards the altar with his best man and was seen acknowledging a guest in the congregation with a nod.
You could hear a pin drop as the 600 guests watched the British prince and American star say "I do" in the historic surroundings of the chapel at Windsor Castle.
At midday, all eyes were turned to the grand door at the West Steps to catch the first glimpse of Meghan as she appeared through the ornate entrance.
Just before the bride arrived, the bridesmaids and pageboys were ushered in by the Duchess of Cambridge, who helped coax them into their positions with an encouraging hand on their shoulder.
The children were handed flowers behind the door when one of the little bridesmaids began to cry, believed to be Harry's two-year-old goddaughter Zalie Warren.
Harry's niece and nephew - George and Princess Charlotte - were among the six bridesmaids and four pageboys, all aged between two and seven.
Harry's goddaughters Zalie and three-year-old Florence van Cutsem, Ms Markle's goddaughters, sisters Remi and Rylan Litt, aged six and seven respectively, and four-year-old Ivy Mulroney - the daughter of Meghan's close friend Jessica Mulroney - were bridesmaids.
The other pageboys were Harry's six-year-old godson Jasper Dyer - the son of Harry's mentor Mark Dyer - and Mrs Mulroney's seven-year-old twin sons Brian and John Mulroney.
The gaggle of children toddled up the aisle behind Meghan through the Nave, before the bride was joined by the Prince of Wales and the pair made their way down the aisle of the Quire to where Harry was waiting.
A few minutes later, there were giggles when the Archbishop of Canterbury conducted the declarations.
A loud and clear "We will" sounded out when the guests were asked if they would support Harry and Meghan.
There were more laughs during the sermon made by preacher Michael Curry, the presiding bishop of the American Episcopal Church Bishop.
The Queen and Meghan's mother, Doria Ragland, sat in the same position on either side of the aisle with stellar views of the proceedings.
The chapel was filled with white garden roses, peonies and foxgloves, with branches of beech, birch and hornbeam, carefully crafted by floral designer Philippa Craddock.
The cascading hedgerow on the West Steps where Meghan arrived matched the glowing floral arch displays on the organ screen in the middle of the chapel - reflecting the surrounding Berkshire countryside.
Harry, resplendent in his military uniform, looked every inch the prince charming next to Meghan in her sumptuous princess gown.
The siblings of Harry's late mother Diana, Princess of Wales were among the guests - Earl Spencer, Lady Sarah McCorquodale and Lady Jane Fellowes, who gave a reading.
The uplifting sounds of a gospel choir singing the moving soul classic Stand By Me, made famous by singer Ben E King but also sung by Beatle John Lennon, was a touching moment.
A few moments later, at 12.40pm, Harry and Meghan were proclaimed to be husband and wife.
Cheers from the crowds outside prompted a laugh from the guests in the congregation, who could hear the excitement of people in the castle grounds.
Walking away from the altar as a newly married couple, Harry and Meghan smiled broadly as they made their way towards the door of the chapel.
The designer of Meghan's gown, Clare Waight Keller for Givenchy, helped to arrange the veil and train perfectly for her exit on to the steps.
After the bride and groom walked through the chapel, the gospel choir sang Etta James' version of the gospel classic Amen/This Little Light of Mine.
The performances prompted enthusiastic applause from the congregation.
