The country’s Crown Princess wowed waiting crowds as she arrived for the event at Amalienborg Palace in Copenhagen yesterday.
With her head clad in a glittering two-century old tiara, the 45-year-old stole the limelight.
She also wore a pair of diamond earrings and a brooch with a picture of her mother-in-law, the Denmark’s Queen Margrethe.
And the look was completed by a breathtaking crimson gown.
Mary was joined by bemedalled husband Prince Frederik, 49, for the traditional banquet.
He looked equally dapper in full military regalia.
Each year, royals join members of the Danish parliament and top officials for the celebration.
Princess Mary is famed for her style and has often been likened in the UK to the Duchess of Cambridge.
And the women not only have their style in common – they both were ‘commoners’ before marrying their husbands.
Mary met Frederik during the 2000 Olympics in Sydney.
The couple maintained a long-distance relationship before Mary moved to Denmark to marry her prince.
A former marketing director, Princess Mary was an account director with advertising agency Young & Rubicam before her royal wedding.
The mother-of-four has just returned from Australia, where she celebrated the festive season with her family.
There has been speculation that Queen Margrethe will abdicate this year and Frederik will take the throne.
At the age of 77, Margrethe is the second-longest reigning monarch in the country’s history.
She first took the throne in 1972 when she succeeded her father and the law was changed to allow female monarchs.
Her husband Prince Henrick was diagnosed with dementia last year.