The images, taken in the White Parlour at the Royal Palace in Oslo, show the royals in Norway's traditional dress.
To mark his milestone birthday, Prince Sverre Magnus has been given a bunad (Norwegian national costume) from the king and queen.
Norwegian bunad design varies by region, and the royal palace shared that the prince has received a “Gråtrøyebunad” from Eastern Telemark, dating back to around 1870.
King Harald, 86, also appointed his grandson to the Grand Cross of the Royal Norwegian Order of St. Olav – one of Norway's highest honours.
Prince Sverre Magnus officially turns 18 on Sunday 3 December but family members, godparents and representatives of the Norwegian authorities and youth organisations are gathered at the palace for a special luncheon on Friday.
In a heartwarming speech, Queen Sonja, 86, said to her grandson: "Magnus, I want to say something important to you and to the other 18-year-olds in our country today. It's good enough to be who you are. The most important thing is to be sure of yourself and listen to your own voice."
Who is Prince Sverre Magnus?
Born on 3 December 2005, the royal is Crown Prince Haakon and Crown Princess Mette-Marit's youngest child.
The royal couple also have Princess Ingrid Alexandra, 19, and Mette-Marit has an older son, Marius Borg Høiby.
Prince Sverre Magnus is currently third in line to Norway's throne behind his sister and his father.
His godparents include Queen Sonja, Queen Maxima of The Netherlands, Crown Prince Pavlos of Greece and Princess Rosario of Bulgaria.
He began his education at kindergarten in Asker, later attending Jansløkka elementary school and Oslo Montessori school.
He is currently a student at Elvebakken Upper Secondary School in Oslo.
Norway's royal website lists his interests as skiing, cycling and water sports.
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