The royal couple are in France to support the growth and position of Danish companies in the French market and to promote relations between the two nations.
They will head up a business delegation in a trade promotional campaign under the title 'Denmark and France – together for a better life and a sustainable future'.
Mary has been appointed to Denmark's Council of State, which means she now has the power to act as regent in the Queen's place, if anything happens to her.
The Danish royals shared the news with their Instagram followers.
In the snap, Mary can be seen smiling proudly as she sits alongside her husband Prince Frederick and Queen Margrethe, who's looking at her lovingly.
Crown Prince Frederik, his brother Prince Joachim and the Queen's sister, Princess Benedikte are the only other members of the family to hold this honour.