The count, whose great-great grandmother was Britain's Queen Victoria, died Saturday night at Angelhom hospital but the cause of his death was not disclosed, The Local reported Monday.
The count was the youngest son of Gustaf VI Adolf of Sweden and Crown Princess Margareta, born Princess Margaret of Connaught and a granddaughter of Queen Victoria.
Although born Prince Carl Johan of Sweden, he lost his title in 1946 when he married journalist Kerstin Wijkmark and went to work as a businessman. They adopted two children, Monica and Christian, and lived in London most of their lives, The Local said.
The count moved back to Sweden and married Countess Gunnila Marta Louise Wachtmeister of Johannishus after Wijkmark died in 1987.
King Carl Gustaf and Queen Silvia released a statement describing Bernadotte as a "dearly beloved family member who meant a lot to the whole family thanks to his friendliness and humor.
"We will remember Carl Johan as a respected and lovable relative whom we always valued deeply, not least due to his knowledge of our family's history, which he always shared so generously," the statement said.
Funeral arrangements were being handled by his immediate family, The Local said.