Fluent in Sanskrit, she contributed important research to the study of antiquities in Afghanistan, Pakistan, India, and Sri Lanka, as well as in Thailand and Indonesia.
She was active in conservation efforts to preserve the archaeological sites of Indus Valley settlements at Mohenjo Daro, working with UNESCO for this purpose.
[6][4] In 1958, she was appointed professor of archaeology at the University of Amsterdam, where she taught the early history of South and South-east Asia.
[8] Johanna van Lohuizen-de Leeuw's contributions to South Asian art and archaeology range over several periods, but she is chiefly remembered for her doctoral work on the Scythian period in North Indian art, as well as her work in establishing the roots of Kusana sculpture in the regions of Gandhara and Mathura.
[4][3] Her work was critical not only in establishing accurate chronologies, but also in tracing and demonstrating the influences of foreign cultures, especially of Hellenic art in depictions of the Buddha, and is now a widely accepted interpretation of the period.
[3] She was the editor of a number of notable academic publications, including Studies in South Asian Culture from 1969 to 1993 and Handbuch der Orientalistik, Kunst und Archäologie from 1970 to 1992.