Take a look at the moment when Denmark's Queen Margrethe II signed her historic abdication, making her son King Frederik X

• Denmark's Queen Margrethe II officially abdicated on Sunday after 52 years on the throne.
• Her eldest son, Crown Prince Frederik, has succeeded her. His new title is King Frederik X.

Queen Margrethe II of Denmark has officially abdicated the throne after 52 years.

Margrethe became Europe's longest-seving living monarch after Queen Elizabeth II died in September 2022.

On Sunday, the Danish royal signed the instrument of abdication at the Christiansborg Palace in Copenhagen in the presence of her eldest son Frederik, 55, who is now king.

Formerly known as Crown Prince Frederik, his new name is King Federick X.

Danish Prime Minister Mette Frederiksen also witnessed the historic moment alongside other members of the Danish government.

According to The Associated Press, after signing the document, the 83-year-old monarch — who will keep her title as queen — rose from her seat at the head of the table and gestured for her son to take her place.

After she did so, King Frederik X's son Christian, 18, moved into his seat as the new heir to the throne, the outlet reports. His new title is Crown Prince Christian.

Before leaving the room, Queen Margrethe said: "God save the king," according to the AP. The Danish royal family's Instagram account also shared a video of the moment.

King Frederik X's Australian-born wife, Princess Mary, has become Queen Mary. The couple's younger children, Princess Isabella, Prince Vincent, and Princess Josephine, are now second, third, and fourth in line to the Danish throne, respectively.

After the instrument of abdication was signed, Frederik was proclaimed king by the prime minister from the palace balcony.

Queen Margrethe made the surprise revelation that she would be stepping down during her annual New Year's Eve speech on December 31, 2023.

King Frederik X made official remarks after succeeding his mother, which was shared by the Danish royal family's Instagram account.

"My Mother, Her Majesty Queen Margrethe II has ruled Denmark for 52 years," he said. "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," he continued.

He said he took great pride in his new role and called on his wife and children for support.

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"I face the future with the knowledge that I am not standing alone. United, bound, to the Kingdom of Denmark," he said.

Margrethe became queen in 1972 at the age of 31 after her father, King Frederik IX, died of complications from pneumonia. Her abdication took place on the 52nd anniversary of her succession.

During her New Year's Eve speech, Margrethe said she underwent "extensive" back surgery in February 2023, influencing her decision to abdicate.

"Everything went well, thanks to the competent health personnel who took care of me. Inevitably, the operation gave cause to thoughts about the future — whether now would be an appropriate time to pass on the responsibility to the next generation," the monarch said.

She is the first Danish monarch to abdicate in over 900 years. The last was King Erik in 1146, who gave up the throne and went to a monastery, according to the Danish royal website.

The changeover has come as drama within the Danish royal family has played out in front of the public.