Eila Pennanen was born in Tampere, daughter of a factory sub-manager, graduated, became a librarian, and worked as an archivist and advertising editor from 1943 to 1951 and as sub-editor for the literary magazine Parnasso in 1952-1955. She married and divorced the translator Juhani Jaskari.
Her debut novel Ennen sotaa oli nuoruus, 1942, depicts students in the 1930s. At the centre of her writing is the Tampere trilogy Himmun rakkaudet, 1971, Koreuden tähden, 1972, and Ruusuköynnös, 1973, which scrutinises the turbulent period of national conflict from a middle-class perspective. As a kind of sequel, Santalahden aika and Kulmatalon perhe were published in 1986 and 1988 respectively, in which she moved on to examine the changed society of the 1980s. She also published the novel Tyttölapsi in 1992 as well as a number of historical novels and also worked on literary translations and literary criticism.