Prince Harry and Meghan Markle tied the knot at Windsor Castle on Saturday in a royal wedding like no other, mixing British pomp and African-American culture in front of a celebrity congregation and cheering crowds.

The new Duke and Duchess of Sussex exchanged vows in St. George's Chapel in a historic ceremony, sealed with a kiss, which brought the biracial US TV star into the heart of the British monarchy.

As more than 100,000 people packed the sun-baked Windsor streets and millions watched worldwide, Queen Elizabeth II and the royal family were joined inside by stars including Oprah Winfrey, Serena Williams, Elton John, George Clooney and David Beckham.

The couple held hands throughout and exchanged vows in a Church of England service modified to reflect the bride's heritage and strong sense of independence.

Firebrand US pastor Michael Curry delivered a full-throttle address invoking slaves and the power of love, and a gospel choir sang classics “Stand By Me” and “This Little Light of Mine”.

Markle began her walk down the aisle alone with her ten bridesmaids and page boys walking behind her flowing white silk dress, designed by Clare Waight Keller at the French fashion house Givenchy.

Her father had been due to meet her half way but after he pulled out because of heart surgery, Harry's father Prince Charles stepped in to escort her the rest of the way to the altar.

Markle's mother, Doria Ragland, looked visibly moved during the wedding and at the end, thanked Charles -- the heir to the throne -- for his role.

With the words “I will”, 33-year-old Harry, and US former actress Meghan, 36, declared they would love, comfort, honour and protect each other.

Archbishop of Canterbury Justin Welby declared them husband and wife -- sparking huge cheers from crowds outside the church, who were watching on big screens.

Markle's father Thomas Markle also followed the wedding on TV and voiced regret he was unable to attend, US celebrity news website TMZ reported.

“My baby looks beautiful and she looks very happy. I wish I were there,” he was quoted as saying.

Smiles at the altar

Harry hand-picked flowers for Markle's bouquet from their home at Kensington Palace, which were mixed with forget-me-nots, his late mother Diana's favourite flowers.

Her five-metre veil also contained floral designs from her native California and all 53 Commonwealth countries.

The groom and his brother Prince William — his best man — wore the blue doeskin frockcoat uniform of a major in the Blues and Royals, the regiment Harry served with in Afghanistan during his 10 years in the British army.

“You look amazing,” Harry told his bride as she arrived.

The couple grinned during Curry's booming address about the power of love in which he quoted civil rights icon Martin Luther King.

“I'm talking about some power. Real power. Power to change the world,” the African-American preacher intoned.

There were no political leaders among the 600 guests but many celebrities, including Idris Elba, James Blunt, Tom Hardy and James Corden.

Some of Markle's former co-stars in US hit television series “Suits” attended, as did Harry's ex-girlfriends Chelsy Davy and Cressida Bonas.

The newlyweds kissed on the church's West Steps after the wedding, before going on a carriage procession ride through Windsor where tens of thousands of flag-waving well-wishers cheered them on.

The streets of the picturesque town were out with bunting, and there was a carnival atmosphere on the Long Walk, the grand tree-lined avenue on the procession route.

“It's been a historic, epic day,” said Leslie Owusu, from nearby High Wycombe.

“It's a union of different cultures, you've got America and England and a fusion of two people that love people and life.”

Kiss and carriage ride

Hundreds of street parties and public screenings were held around Britain where the wedding is a welcome respite for a country still burdened by austerity and divided over Brexit.

Revellers also packed into bars to watch as far afield as Sydney, Hong Kong and Markle's native Los Angeles, for what is likely to be the last big British royal wedding for a generation.

In Windsor, thousands of fans bagged their spots by dawn, bearing rugs and picnics, Union Jack flags and patriotic paraphernalia, and the bubbly was flowing freely.

“It made me really emotional when I saw them coming past,” said Helen Oliver, 50.

Kristin Glithero, 45, from nearby Wokingham, was not the only one wide-eyed at Curry's fiery address.

“His message was lovely and the way he delivered it was very powerful,” she said. “But maybe too long for the British public!”

Canapes and Meghan's speech

The queen hosted a lunchtime reception at the castle, where Elton John performed to guests eating canapes including Scottish langoustines, English asparagus and Windsor lamb.

The royal couple cut the lemon and elderflower cake, while Charles and Harry made speeches introduced by William.

In another break with convention, Meghan was due to speak at the evening reception for 200 family and close friends.

“She's got her own voice, a personality, and I think all that made a huge impression on everybody which is why the crowds here are amazing,” said Shrabani Basu, a Commonwealth historian.

The couple met on a blind date in July 2016 and had a whirlwind romance, criss-crossing the Atlantic as she continued filming in Toronto.

Harry was scarred by his mother Diana's death in a Paris car crash in 1997 when he was just 12, and he had to mourn in the full glare of the world's media.

His wedding featured a hymn used at Diana's funeral, at which he and William had walked behind her casket.

Sixth in line to the throne, Harry is one of the most popular royals, while Markle, a divorcee, is seen as a breath of fresh air for the monarchy.

Sam Lukes, 28, from nearby Reading, said: “He's marrying someone that's representative of modern society”.