Margaret "Margit" Abenius was born in Orsa, Sweden, a daughter of chemist Wilhelm Abenius.
She studied at Uppsala University and earned a doctorate in literary history in 1931. She is best known for her biography and other works on the Swedish poet and novelist Karin Boye. Her biography of Boye was originally published in 1950. She also edited Boye's collected works in a total of 11 volumes from 1947 to 1949. Along with Olof Lagercrantz, she published Boye: Memories and Studies. Margit Abenius also served as the literary columnist for Swedish radio and worked for the Bonniers literary magazine from 1933. A selection of her essays was published in 1940 under the title Contacts. She also wrote books about Linnaeus and Simone Weil, and translated Simone Weil's Gravity and Grace.