Bertha Wegmann was born in Soglio, Switzerland, but moved to Copenhagen with her family when she was five years old. In 1862 she received her first artistic training at Professor Frederik Ferdinand Helsted’s (1809-1875) Drawing School, encouraged by her art-loving father. In 1867 she travelled to Munich, to further develop her artistic skills, living in the city until 1881. Initially, she received drawing lessons from the German painter Johanna Unger (1836–1871) and painting lessons from the Hungarian painter Alexander von Liezen-Mayer (1839–1898). In 1869 she enrolled at the Damenakademie [The Women’s Academy] in Munich, where she was taught by the German painter Wilhelm von Lindenschmit the Younger (1829–1895).

In her years living in Munich, B. Wegmann went on several study trips to Tyrol, Bavaria, Brittany, Florence and Dresden, often accompanied by the Swedish painter Jeanna Bauck (1840–1926). From 1879 onwards they often travelled to Paris. J. Bauck and B. Wegmann settled down in Paris in 1880–81, spending their summers in Écouen, north of Paris. In Paris, B. Wegmann received artistic training at Académie Trélat. She exhibited at the Salon de Paris for the first time in 1881, and here she received an honourable mention for the painting Kunstneren Jeanna Bauck [The Artist Jeanna Bauck, 1881]. In the following year, she exhibited the painting Anna Seekamp. Kunstnerens søster [Anna Seekamp, the Artist’s Sister, 1882] at the Salon, where she received a third-class medal. In 1883 the painting was exhibited at Charlottenborg in Copenhagen, and here she was the recipient of Den Thorvaldsenske Udstillings-Medaille [The Thorvaldsen Medal]. In 1887 she became the first female member of Akademiets Plenarforsamling [The Academy Plenary]. B. Wegmann took part in the World’s Columbian Exposition in Chicago in 1893, and the Exposition Universelle in Paris in 1889 and 1900, on both occasions receiving a silver medal for her work.

In 1892 she was the first woman in Denmark to receive Den Kongelige Fortjenstmedaljen i guld [The Royal Medal of Merit in Gold]. She was a member of the board of Tegne- og Kunstindustriskolen for Kvinder [Arts and Crafts School for Women] from 1887 to 1907 and was active throughout her career in the fight for women’s rights to education and access to art education. B. Wegmann died in 1926 in Copenhagen. She bequeathed her own collection of her artworks to the Danish museums, but only a few museums accepted her offer: the art museums in Aarhus, Odense and Aalborg, today called ARoS Aarhus Art Museum, Brandts Art Museum and Kunsten Museum of Modern Art Aalborg.