Joshi received his Ph.D. in Physics from Allahabad University in 1962. Joshi's broad areas of interest are condensed matter and collision processes. His early research was in the study of phonons in metals and insulators. Later, he studied electronic states in disordered systems and electron correlation in narrow band solids. He has also worked on Surface states and Segregation in materials. Joshi conducted studies on excitation and ionization processes in atoms, ions, and molecules. His current research interests lie in strongly correlated electron systems, such as high temperature superconductors, and also in nanotechnology, especially electron transport in quantum dots and nanotubes.
Joshi has supervised the Ph.D. theses of twenty scholars and has published more than 190 research papers. He was Professor of Physics at the Indian Institute of Technology, Roorkee from 1967 to 1986. He was the Director of the National Physical Laboratory from 1986 to 1991. In 1991, he was appointed the Director General of the Indian Council of Scientific and Industrial Research. After retiring in 1995, he was awarded the Sarabhai Research Professorship in Physics. He currently works on condensed matter theory at the National Physical Laboratory in New Delhi.
He was elected Fellow of the Indian National Science Academy in 1974. He was the Secretary of the Academy from 1983 to 1986 and its Foreign Secretary from 1989 to 1992. He was elected President of the INSA in 1993. He has been a Fellow of the Indian Academy of Sciences since 1974, and was Vice President from 1989 to 1991. Joshi was president of the Indian Physics Association from 1989 to 1990. He is president of the Materials Research Society of India. Joshi is a Fellow of the Third World Academy of Sciences, and a Foreign Member of the Russian Academy of Sciences.