Rangarajan's research areas include nonlinear dynamics, chaos, time series analysis, and computational biology.

As a co-principal investigator of the Indo-French Cyber University Project, he helped establish the first inter-continental satellite-based courses.

Rangarajan is currently the director of the Indo-French Centre for Applied Mathematics (IFCAM),[5] the first Unités Mixtes Internationales of CNRS in India.

IFCAM supports joint research projects between India and France in the broad area of applied mathematics.

[7] Rangarajan is an honorary professor of the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India.