Two billion TV viewers worldwide watched as Kate swept up the aisle of Westminster Abbey wearing an ivory and white satin dress with long lace sleeves, a veil and flowing train.
William, dressed in a scarlet military uniform, mouthed "you look beautiful" to his bride, then the couple solemnly exchanged their vows before Archbishop of Canterbury Rowan Williams pronounced them man and wife.
More than one million people lined the streets of London to wish the newlyweds well, police said.
The future king and queen later kissed twice on the balcony of Buckingham Palace to the delight of hundreds of thousands of wellwishers -- one more kiss than William's parents Charles and Diana exchanged when they wed in 1981.
Royal Air Force planes streaked low above the palace in honour of the royal newlyweds, who will now be known officially as the Duke and Duchess of Cambridge.
The display of pomp mixed with genuine affection offers the scandal-hit royals a chance at renewal after Charles and Diana's traumatic public split and her tragic death in a car crash in Paris 1997.
The marriage completes a romance that began eight years ago when William, the second-line to the throne, and his "commoner" bride were both still students at St Andrews University in Scotland.
"They will make the monarchy fashionable again. It's good for the country," said Louise Akehurst, 25, an administrator from London who was in the crowd.
Yet the absence of Diana was keenly felt despite the joyful atmosphere of Friday's service, with several pieces of music related to her life taking centre stage in the wedding of her eldest son.
Around 1,900 guests crammed into Westminster for the service, including musician Elton John who sang "Candle in the Wind" at Diana's funeral service there 14 years ago.
Footballer David Beckham and his fashion designer wife Victoria, "Mr Bean" actor Rowan Atkinson, film director Guy Ritchie and Australian Olympic swimming icon Ian Thorpe were also among those in the abbey.
Queen Elizabeth II, William's grandmother, led the royal contingent, while there were also around 40 foreign royals and dozens of dignitaries.
William Arthur Philip Louis -- as the second in line to the throne was called during the service -- arrived at the abbey 45 minutes early accompanied by his younger brother and best man Prince Harry.
Despite the 28-year-old William's job as a Royal Air Force search and rescue helicopter pilot, he wore the red tunic of the Irish Guards infantry regiment, the uniform of his highest-ranking military position.
Kate, 29, had waved to the crowd as she arrived at the abbey with her father Michael in a Rolls-Royce limousine, but all eyes were on her dress.
Palace officials confirmed her robe was by Sarah Burton at Alexander McQueen, the iconic British designer who committed suicide last year.
Kate took four minutes to walk down the aisle, which was lined with trees especially brought in to create the feel of an English garden.
The first hymn -- "Guide me, O thou great redeemer", was the last sung at Diana's funeral.
The couple both said "I will" before repeating their vows to love and cherish each other. William briefly struggled to fit the ring, made from a nugget of Welsh gold, over her finger.
Kate, however, did not promise to obey her husband in her marriage vows -- following in the footsteps of Diana, who married Charles on July 29, 1981 at St Paul's Cathedral.
After the service, the newlyweds climbed into a horse-drawn open carriage to make the journey from the abbey to Buckingham Palace along the Mall, as the crowds cheered them loudly.
When the couple appeared on the balcony Kate could be seen mouthing "Wow" at the ocean of people in front of them. William then appeared to ask her "Shall we kiss?" before embracing his bride, following it up with another shortly afterwards.
Sandra Russell, 65, who is of French-British nationality, said she thought the marriage would be successful because Kate is "much older than Diana was at the time, much more mature and they are marrying for love."
"Charles was under the pressure of his family. People here are still angry at him, and Camilla (his second wife) too. I hope William will be the next king."
About 5,500 street parties took place across Britain on Friday, including in the Scottish university of St Andrews, where William and Kate met, and in the bride's home village of Bucklebury.
