She was the daughter of colonel Patrik Constantin Fries and Beata Maria Borgström. She graduated from Åhlinska flickskolan in Stockholm 19 May 1874. She studied language and art by travelling to Paris and Leipzig and was a language teacher at Wallinska skolan in 1875-1877. The universities in Sweden had been opened to both genders in 1870. Fries enlisted as a student at Uppsala University 12 October 1877. She studied history, Nordic language and political science and was given the scholarship Kraemerska stipendiet. She became the first female Ph.D. in Sweden 31 May 1883. She was a teacher in history at Wallinska skolan in Stockholm 1884-1886 and at Åhlinska flickskolan from 1885; in 1890, she became its principal.
In 1884, she was one of six to summon the first meeting of the feminist movement Fredrika-Bremer-förbundet; she initiated the foundation of Svenska kvinnors nationalförbund (Swedish Council of Women) in 1896, and one of the five co-founders of the Nya Idun society.
From 1881, she was active in the feminist paper of Sophie Adlersparre, Tidskrift för hemmet, mainly contributing with biographies of women, and she was also joint editor of the paper in 1883-85. She contributed with articles as a freelancer to various papers, such as Dagny (paper) 1886–95, Framåt (paper) 1886, Verdandi (paper) 1888, Hemåt (paper) 1892, Nya Idun 1891–92, Stockholms Dagblad 1884–85 and Aftonbladet 1885 as well as in the dictionary Nordisk Familjebok.
In 1886 and 1899–1900, she lectured about the 17th- and 18th-century at Pedagogiska lärokursen in Stockholm.
- "Märkvärdiga qvinnor" 2 vol (1890–1891)
- "Sverges sista häxprocess i Dalarne 1757-1763" 1893.
- "Den svenska odlingens stormän" Lefnadsteckningar för skola och hem. (1896-)
- "Teckningar ur svenska adelns familjelif i gamla tider" (del 1 1895)
Del två gavs ut efter hennes död av fadern:
- "Teckningar ur svenska adelns familjelif i gamla tider" (del 2 1900)
- "Svenska kvinnor" 1920
- "Om samskolor" Dagny nr 2 1892
- "Kvinnan och försvaret. Dagny, nr 8 1892
- "Flickskolemötet i Lund sommaren 1893" Dagny, nr 6 1893
- "Några blad ur svenska kvinnans historia under sjuttonhundratalet" Dagny nr 4-5 1895
- "Kvinnliga elementärundervisningen i Frankrike" (reseberättelse) 1885
- Works by Ellen Fries at Project Gutenberg
- Works by or about Ellen Fries in libraries (WorldCat catalog)