The reason for the hospital visit has not been made public, but the Crown Princess is seriously ill with pulmonary fibrosis.
The visit lasted a little over two hours, before the family left the hospital.
Mette-Marit's health has forced her husband, Crown Prince Haakon, to cut short a planned trip to Japan. In addition, her daughter, Princess Ingrid Alexandra, has returned early from studies in Australia on short notice. They were both by Mette-Marit's side when she arrived at Rikshospitalet.
Haakon landed in Oslo on Thursday morning after his trip to Japan.
"I find strength in being together," he said on Wednesday, according to NRK.
