She is remembered for her pioneering research into the culture of the Sámi peoples of northern Sweden, including their relationship with those in neighbouring Nordic counties.
In 1981, she was appointed professor of ethnology at Umeå University where she remained until her retirement in 1990, both teaching and undertaking further research.
They returned to Uppsala in 1956 where, inspired by her ethnology teacher Åke Campbell [sv], Phebe Fjellström was able to undertake research on Sámi culture.
Her research examined the connections between the Sámi peoples and their neighbours in the Nordic countries as well as cultural contacts with the rest of Europe.
Her approach was based in part on the work of the ethnologist Sigfrid Svensson [sv] from Lund who had revealed connections between Scanian and Sámi silver.