As he has been for the last decade, the royal was accompanied by his elegant consort, who waved to the tens of thousands of well-wishers.
With tears in her eyes an emotional Princess Beatrix, who has reigned for 33 years, told the crowds below: "Today I leave room for a new generation. My son now assumes responsibility for this new role."
A huge cheer went up when it was her successor's turn to speak. After kissing his mother warmly on the cheek, Willem-Alexander passed on the nation's "heartfelt thanks" for her three decades of service.
As her son spoke, Beatrix again blinked back tears and held hands with her daughter-in-law Maxima. For a moment amid the pomp and ceremony, they seemed like any ordinary family, celebrating a private moment.
The crowds looking on in Dam Square, were decked out in the country's national colour, orange. It could be seen on fake crowns, hats, garlands and banners, as they showed their support for the royals gathered on the balcony which was decked in fruit, flowers and foliage.
Many were overcome with emotion, crying as they welcomed the first male head of state for more than120 years.
A rousing band then began to play the national anthem as the royal trio sang, all holding hands.
Once the anthem has finished, Princess Beatrix retreated inside the palace, making way her for her three granddaughters, Princess Alexia, Princess Ariane and Princess Amalia who were dressed in adorable matching yellow outfits.
Making her first balcony appearance as the heir to the throne, Amalia, nine, enthusiastically waved to the people she will one day rule. As she did so, King Willem-Alexander supportively kissed his daughter on the head.