The world’s eyes have stayed focused on the young royals ever since, watching as William, 33, and Kate, 34, traveled the world and grew their family. As the royals mark their milestone today privately, at their Anmer Hall home, take a look at five momentous moments from their five years of wedded bliss.
1. Double Buckingham Palace Wedding Kisses
In a beautifully executed wedding, William and Kate’s April 29, 2011, balcony kiss was the one wildcard, and it did not disappoint. The heir to the British throne first exchanged a short peck with his beloved bride. Two minutes later, responding to chants from the crowd of "Kiss her again," the newlyweds locked lips.
The Abbey bells rang, the overhead fighter planes hummed and the crowd erupted in cheers and became a sea of waving flags.
2. Birth of Prince George
The world got its first glimpse of the little prince the day after George’s birth, when the family left the hospital with the prince swaddled in a white blanket in his mother's arms.
"It's very emotional," Kate said at the time. "It's such a special time. I think any parent will know what this feeling feels like."
3. Birth of Princess Charlotte
Born at 8:34 a.m. local time on May 2, 2015, Her Royal Highness Princess Charlotte of Cambridge weighed 8 pounds, 3 ounces.
4. Charitable Work
Prince William is also focused on raising awareness of bullying, cyber bullying and suicide rates among young men.
Kate is channeling her energy on the mental well-being of young people. The duchess has participated in two public service announcements to draw attention to the challenges faced by young children struggling with mental illness.
This month, the duke and duchess joined with Prince Harry to launch The Heads Together campaign to help tackle the stigma surrounding mental illness. The royals donned blue Heads Together headbands in a video released to announce the campaign, which is supported by their Royal Foundation.
5. Country Life at Anmer Hall
After the birth of Princess Charlotte in May 2015, Prince William and Kate brought their family to their country home, Anmer Hall, a 10-bedroom home on Queen Elizabeth II's Sandringham Estate in Norfolk, England.
The couple completed a renovation of the property, which includes a conservatory, a new kitchen and a new roof. In January, Prince George began nursery school at the nearby Westacre Montessori School in Norfolk.
The home, which has plenty of space for visiting relatives, is also close to where William works as a pilot for East Anglian Air Ambulance. It is also near the homes of several of William and Kate's closest friends. The royals have been spotted in local Norfolk shops and visiting the local playground.
Bonus: Royal Trips
Australia and New Zealand, 2014
Prince William and Kate took a 9-month-old Prince George on his first official royal trip overseas in April 2014.
While Down Under, William and Kate unveiled a plaque in Adelaide renaming the city's center square as Prince George Plaza and also accepted on George's behalf a green, custom-made skateboard that featured "George" on the bottom flanked by Australian flags and kangaroos. The Duke and Duchess of Cambridge also helped officially open a new enclosure at Sydney's Taronga Zoo, which was named the Prince George Bilby Exhibit.
Prince William and Kate in April undertook a week-long tour of India and Bhutan on behalf of Prince William’s grandmother, Queen Elizabeth II.
The duke and duchess traveled solo, leaving Prince George and Princess Charlotte behind in the U.K. under the care of their nanny and Kate's parents, Carole and Mike Middleton. William and Kate drew attention to anti-poaching efforts during a safari in Kaziranga National Park, hiked to the Tiger’s Nest Monastery in Bhutan and visited the Taj Mahal in India during their busy tour.
"When Catherine and I were married, India was the first place on Catherine's list that she told me that she wanted to visit," William told guests at a charity gala that drew Bollywood celebrities. "Two children and five years later, we have finally made it –- and we are both honored to be here."