The former monarch attended a reception prior to the concert of the European Youth Orchestra in Amsterdam on Wednesday evening.
She put on a brave face for the event, laughing and smiling with attendees and organisers.
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The 75-year-old wore a glamorous black ensemble for the occasion and accessorised with a dark pearl necklace and earrings.
She graciously accepted a pretty bunch of flowers and interacted genially with her fellow guests.
Her last public appearance at the funeral of her second son Prince Friso on 16 August was a rather more sombre occasion.
The Dutch royal family united to pay their respects to the 44-year-old royal who had been in a coma since February 2012 following a ski accident.
Princess Beatrix held the hand of Prince Friso and Princess Mabel's youngest daughter Zaria as they were photographed on the sad occasion.
Earlier this year, the Dutch royal family made the headlines when then Queen Beatrix abdicated in favour of her eldest son King Willem-Alexander.
Two days of national celebrations saw Willem-Alexander and his wife Maxima become the youngest monarchs in Europe.