Princess Mary was among the many royals who gathered to mourn the passing of Prince Richard.
The 82-year-old was the husband of Princess Benedikte, the younger sister of Denmark’s Queen Margrethe.
Scandinavia’s glittering monarchs gathered in the German town of Bad Berleburg for the service.
Australia’s Princess joined her husband Prince Frederik for the farewell. The mum-of-four looked very elegant in sleek all black ensemble, teamed with a tasteful hat.
Prince Richard and Princess Benedikte lived in Germany and they shared three children.
Danish media reported that the Prince was at his home, Berleburg Castle, with his only son Gustav, when he suddenly passed away.
It is believed the 82-year-old had faced numerous health issues over the years, including battling cancer twice.
Richard’s 72-year-old wife was in her native of Denmark at the time.
The Princess’ private secretary commented that in light of the “sudden” death, the flag at Amalienborg Palace in Copenhagen would fly at half-mast as a mark of respect.
Along with his wife, who he met in 1966 and married two years later, Richard is survived by his three children Prince Gustav, Princess Alexandra and Princess Nathalie.
To commemorate the beloved royal, Queen Maxima, King Willem Alexander, Queen Silvia and Princess Madeleine of Sweden, all attended the Evangelical City Church service.