Queen Margrethe II 83, has formally abdicated in favour of her 55-year-old son, Crown Prince Frederik.
The Crown Prince was proclaimed King Frederik X of Denmark by Prime Minister Mette Frederiksen from the balcony of Christiansborg Palace in Copenhagen.
King Frederik and his wife, now Queen Mary, were visibly moved by the cheers from the crowd as they appeared alongside their four children, Crown Prince Christian, 18, Princess Isabella, 16, and 13-year-old twins, Prince Vincent and Princess Josephine.
See the historic moment in the clip below...
It came just an hour after Margrethe, who has reigned for 52 years, signed a formal declaration at a Council of State meeting.
It was an emotional moment as a teary-eyed Margrethe signed the document, before getting up from her chair and declaring "God Save The King!"
Frederik then appeared to blink back tears as he sat in the seat at the head of the table, with his eldest son and now heir to the Danish throne, Prince Christian, by his side.
Prince Christian is now Crown Prince of Denmark while his younger siblings, Princess Isabella, Prince Vincent and Princess Josephine are now second, third and fourth in line to the Danish throne respectively.
The Danish abdication as it happened
Huge cheering crowds gathered to watch the Danish royal family make their way to Christiansborg Palace. Incoming King, Frederik was captured as he peeked out of the window.
Unlike the British monarchy, there is no formal coronation for any new monarch within the Danish royal family. Historian Marlene Koenig previously told HELLO!: "The UK monarchy is unique when it comes to crowning the Sovereign. In its history, Parliament has passed several acts that require the sovereign have a coronation ceremony after the accession.
"The first Danish coronation was in 1170 and the last in 1840 for King Christian VIII and his second wife, Caroline Amalie of Schleswig-Holstein-Sonderburg-Augustenberg, who succeeded in 1839 and died in 1848. The throne passed to his thrice-married son, Frederik VII, who had no surviving children."
She added: "Denmark was an elective monarchy until 1660. These elective monarchs had full coronation ceremonies, but the change to the hereditary monarchy in 1660 brought a new ceremony. The king and queen were anointed but no crowning. They came into the church wearing their crowns. By 1849, when Frederik VII succeeded, Denmark was a constitutional monarchy, and the anointing ceremony was abolished."
Queen Margrethe made her way from from Christian IX's Palace at Amalienborg to Christiansborg Palace in the Golden Wedding Anniversary Coach, escorted by the Guard Hussar Regiment’s Mounted Squadron.
The Golden Wedding Anniversary Coach was a gift from master artisans in Copenhagen for the golden wedding anniversary of The King and The Queen at that time, Christian IX and Queen Louise, on 26 May 1892.
At a Council of State meeting, Queen Margrethe signed a declaration of abdication in the presence of incoming King Frederik X and Crown Prince Christian.
Emotions were high as Margrethe signed the document before standing up from her chair at the head of the table to leave the seat for the new King Frederik, as his son Christian moved into his seat.
Thousands of people gathered in front of Christiansborg Palace to witness the moment that Frederik was proclaimed King by the Prime Minister, Mette Frederiksen.
Wiping away tears as the crowd cheered, Frederik delivered his first address as King, saying: "My mother, Her Majesty Queen Margrethe II has ruled Denmark for 52 years. For half a century, she has kept track of the times with our shared heritage as an outlet. She will forever be remembered as a regent beyond the ordinary. My mother has managed to walk in one with her kingdom.
"Today the throne goes on. My hope is to become a unifying king of tomorrow. It’s a task I’ve been approaching my whole life. It's a responsibility I take on with respect, pride and great joy. It's a deed I will do my best and carry through the confidence I encounter. I'm going to need all the support I can get from my beloved wife, from my family, from you and from that which is bigger than us. I face the future with the knowledge that I am not standing alone. United, bound, to the Kingdom of Denmark."
Queen Mary then joined her husband on the balcony, where the couple also shared a sweet kiss. According to Copenhagen magazine Billed Bladet, Mary chose to wear a dress designed by Soeren Le Schmidt and sewn by Birgit Hallstein.
The sublime, full-length dress featured a sweeping neckline and regal draped fabric that bore a striking similarity to her Uffe Frank wedding gown, which was also stitched by Hallstein.
By wearing white for the accession, she followed a trend set by other Queens of Europe, including Queen Letizia of Spain and Queen Mathilde of Belgium.
Frederik and Mary were later joined on the balcony at Christiansborg by their four children, who smiled and waved at the crowd.
After travelling back to Amalieborg from Christiansborg, the new King and Queen made a second balcony appearance.
When did Queen Margrethe announce her abdication?
Frederik's accession comes just two weeks after Margrethe shocked the world when she announced her decision to abdicate in her New Year's address – the first in the Danish monarchy's history in nearly 900 years.
Margrethe said: "In February this year I underwent extensive back surgery. It went well, thanks to the skilled healthcare staff who took care of me. Of course, the operation also gave rise to thinking about the future - whether the time had come to leave the responsibility to the next generation.
"I have decided that now is the right time. On 14 January 2024 – 52 years after I succeeded my beloved father – I will step down as Queen of Denmark. I leave the throne to my son Crown Prince Frederik."
It was also confirmed by the Danish royal palace that the queen told her sons, Crown Prince Frederik and Prince Joachim, of her plans just three days before her announcement.
Frederik, who has been heir to the throne since the age of three, will celebrate his 20th wedding anniversary with wife Mary in May.
The Danish royal met Tasmania-born Mary during the Sydney 2000 Olympics at the Slip Inn pub.