Margaretha was born on 31 October 1934 at Haga Palace in Haga Park, Stockholm, as the first child of Prince Gustaf Adolf, Duke of Västerbotten, and his wife Princess Sibylla of Saxe-Coburg-Gotha; paternal granddaughter of Crown Prince Gustaf Adolf of Sweden and his late wife Princess Margaret of Connaught; maternal granddaughter of Duke Carl Eduard I, Duke of Saxe-Coburg and Gotha and his wife Princess Victoria Adelaide of Schleswig-Holstein; she was born during the reign of her paternal great-grandfather King Gustaf V of Sweden.

Although the eldest child, as a female, she was never in line to the throne according to the Swedish constitution current at the time.

[2] She met her future husband, the businessman John Ambler, ten years her elder, at a dinner party in the United Kingdom in 1963 and their engagement was announced on 28 February 1964.

As a result of her unequal marriage, she lost her style of Royal Highness and the King gave her the courtesy title of Princess Margaretha, Mrs. Ambler.

The couple had three children: In June 1960, Margaretha, with her first cousin Princess Margrethe of Denmark and her second cousin once removed Princess Astrid of Norway, toured the United States on the occasion of the first transatlantic flight by Scandinavian Airlines.