Sonja was born in Oslo on 4 July 1937, the daughter of clothing merchant Karl August Haraldsen (1889–1959) and Dagny Ulrichsen (1898–1994).
She grew up at Tuengen Allé 1B in the district of Vinderen in Oslo and completed her lower secondary schooling in 1954. She received a diploma in dressmaking and tailoring at the Oslo Vocational School, and a diploma from École Professionnelle des Jeunes Filles (a finishing school) in Lausanne, Switzerland. There, she studied accounting, fashion design, and social science. She returned to Norway for further studies and received an undergraduate degree (French, English and Art History) from the University of Oslo.
Sonja became engaged to then Crown Prince Harald in March 1968. They had been dating for nine years, although their relationship had been kept secret because of her non-royal status. The Crown Prince made it clear to his father, King Olav V, that he would remain unmarried for life unless he could marry her. This would in effect have put an end to the rule of his family, and likely to the monarchy in Norway, as Harald was the sole heir to the throne. Faced with having to choose one of his relatives from the Danish Royal Family, the Dukes of Schleswig-Holstein or even the Grand Dukes of Oldenburg as his new heir in place of his son, Olav V consulted the government for advice and, as a result, the couple was wed on 29 August 1968, at Oslo Domkirke in Oslo. She thus acquired the style of Royal Highness and the title of Crown Princess of Norway.
Following the death of King Olav V on 17 January 1991, Sonja became Norway’s first queen consort in 53 years. Queen Sonja accompanied King Harald V when he swore his oath to uphold the Constitution in the Storting on 21 January 1991. It was the first time in 69 years that a Norwegian queen had been present in the Storting. Since his accession, Queen Sonja has accompanied the King to the formal opening of the autumn session of the Storting and the reading of the Speech from the Throne.
In accordance with their own wishes, the King and Queen were consecrated in Nidaros Cathedral in Trondheim on 23 June 1991. Following the consecration, the King and Queen conducted a 10-day tour of Southern Norway. In 1992, the entire Royal Family conducted a 22-day tour of Norway’s four northernmost counties.
The Queen accompanies the King on official state visits abroad. She acts as the hostess when foreign heads of state officially visit Norway. The Queen has also given lectures on Norway as a tourist destination on several occasions during official state visits abroad.
In 2005, Queen Sonja became the first queen ever to visit Antarctica. The Queen was there to open the Norwegian Troll research station in the country’s Antarctic dependency, Queen Maud Land. The Queen flew in on one of the Royal Norwegian Air Force’s C-130H Hercules transport aircraft, landing at Troll Airfield.