 Paranjpye was elected a Fellow of St John's College in November 1901 and stayed as such until 1907, but returned to India to become a professor of mathematics at Fergusson College in 1902.One of the earliest Indian documentary film makers, H. S. Bhatavdekar, made silent documentary films, "Return of Wrangler Paranjpye" (1902) and "Delhi Durbar of Lord Curzon" (1903), featuring R. P.

In 1907, R. P. became the first librarian of the Indian Mathematical Society at Fergusson College.He became the college's principal, and stayed in that position for two decades, until 1926.