WATCH: The Royal Wedding In Videos

Britain’s Prince Harry and Meghan Markle became husband and wife in a star-studded Windsor Castle ceremony on Saturday, filled with traditional pomp and modern twists — and watched the world over.

The new Duke and Duchess of Sussex exchanged vows at the altar in St. George’s Chapel in an emotional event that brought the biracial US TV star into the heart of the British monarchy.

As some 100,000 packed the sun-baked Windsor streets outside, Queen Elizabeth II and the royal family were joined by stars including Oprah Winfrey, Elton John, George Clooney and David Beckham.

The couple held hands throughout and exchanged vows in a traditional Church of England wedding featuring unusual turns.

US pastor Michael Curry delivered an impassioned address and a gospel choir sang “Stand By Me”.

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

Markle’s mother, Doria Ragland, looked visibly moved.

Archbishop of Canterbury Justin Welby, the Church of England’s spiritual leader, declared them legally wed, saying: “They have declared their marriage by the joining of hands and by the giving and receiving of rings.

“I therefore proclaim that they are husband and wife.”

With her father recovering from a heart operation in Mexico, Markle walked down the aisle on her own, before being accompanied to the altar by Harry’s father Prince Charles.

Her flowing white dress was designed by Clare Waight Keller at the French fashion house Givenchy. Made from a double bonded silk cady, it contains floral designs from all 53 Commonwealth countries.

The new duke and duchess will spend much of their time working with youth in the Commonwealth.

Her bouquet included flowers hand-picked by Harry from the gardens of Kensington Palace.

Smiles at the altar

Waiting at the altar, Harry was wearing the blue doeskin frockcoat uniform of a major in the Blues and Royals, the regiment he served with in Afghanistan during his 10 years in the British army.

His brother and best man Prince William wore a matching uniform, emphasising the brothers’ close bond.

Harry looked at Meghan and smiled as they heard how marriage is “the foundation of family life in which children are born”.

The couple held hands and giggled at the altar and smiled as they heard Curry’s firebrand address.

Stars in the pews included Serena Williams, Idris Elba, James Blunt, Tom Hardy and James Corden.

Harry’s ex-girlfriends Chelsy Davy and Cressida Bonas also attended.

Up to 100,000 people, many decked out in patriotic paraphernalia, packed the streets of Windsor to get a glimpse of the newlyweds on their open-top carriage tour through the town afterwards.

Some well-wishers had camped overnight.

Revellers also packed into bars to watch the wedding as far afield as Sydny and Hong Kong.

“After the week she’s had, she needs some support,” said Karen Wallace, 53, from Chicago.

Markle’s ring has been made with Welsh gold, as is traditional for royal weddings, while Harry’s is made of platinum.

Before the wedding, Queen Elizabeth conferred the title Duke of Sussex on her grandson Harry, meaning Markle will be known as the Duchess of Sussex.