With Karl Kerenyi and Walter Burkert, Harrison is one of the founders of modern studies in Ancient Greek religion and mythology.

Her governesses taught her German, Latin, Ancient Greek and Hebrew, but she later expanded her knowledge to about sixteen languages, including Russian.

Mary Beard described Harrison as "the first woman in England to become an academic, in the fully professional sense – an ambitious, full-time, salaried, university researcher and lecturer".

In 1888, she began to publish in the periodical that Oscar Wilde was editing called The Woman's World on "The Pictures of Sappho".

She ended up translating Mythologie figurée de la Grèce (1883) by Maxime Collignon as well as providing personal commentary to selections of Pausanias, Mythology & Monuments of Ancient Athens by Margaret Verrall in the same year.

In responding to an anti-suffragist critic, Harrison demonstrates this moderate ideology:[The Women's Movement] is not an attempt to arrogate man's prerogative of manhood; it is not even an attempt to assert and emphasize women's privilege of womanhood; it is simply the demand that in the life of woman, as in the life of man, space and liberty shall be found for a thing bigger than either manhood or womanhood – for humanity.

She had been a candidate for the Yates Professor of Classical Art and Archaeology at University College London after Reginald Stuart Poole had died in 1895.

[14] The hiring committee had recommended Harrison to the position, but that decision was blocked by Flinders Petrie in favor of Ernest Gardner.

[14] Harrison's first monograph, in 1882, drew on the thesis that both Homer's Odyssey and motifs of the Greek vase-painters were drawing upon similar deep sources for mythology, the opinion that had not been common in earlier classical archaeology, that the repertory of vase-painters offered some unusual commentaries on myth and ritual.

Harrison and her generation depended upon anthropologist Edward Burnett Tylor (who was himself influenced by Darwin and evolutionary ideas) for some new themes of cultural evolution, especially his 1871 work, Primitive Culture: researches into the development of mythology, philosophy, religion, language, art, and custom.

It may also be that the contents of this mystical apprehension cannot be put into language without being falsified and misstated, that they have rather to be felt and lived than uttered and intellectually analyzed; yet they are somehow true and necessary to life.

Harrison never visited Italy or Greece after the war: she mostly wrote revisions or synopses of previous publications, and pacifist leanings isolated her.