In 1873–1875, Karolina Widerström was a student at the Royal Central Gymnastics Institute, and in 1875–1877, she was the assistant to Professor Branting.

[2] Widerström wanted women and girls to know more about their own bodies, to dress more healthily, and to receive the same rights and possibilities as men.

[2] Concerned for women's health issued, she was a strong supporter of the Swedish Dress Reform Association and a vocal force in writing medical articles advocating against tight laced corsets, which at this point in time was a serious health issue.

[3] From about 1900, Widerström was active in the struggle to abolish the so-called reglementation of prostitutes, that is to say the forced registration and regular examination for venereal diseases of prostitutes, a system highly debated among women's rights activists at the time, which organized in the Svenska Federationen to oppose it.

She was elected chairwoman of the Swedish Society for Woman Suffrage in 1918, one year before the women suffrage was granted in Sweden in 1919, and became its last chairwoman when she stepped down after the organisation was dissolved in 1921, when the purpose of the organisation was fulfilled and both genders exercised the right to vote in the 1921 election.