He has served as the Dean and Director of Centre for Advanced Study in Geology, University of Sagar, India; Head of Department of Geology, University of Dar es Salaam, Tanzania; Director, State Mining Corporation, Tanzania and Adviser on Environment and Technology, Mozambique.

Later he did post-doctoral work on lead isotopes with Clair Patterson in Caltech in 1957, and Rb – Sr and K – Ar dating with Stephen Moorbath in Oxford, England, in 1963.

Using geochemical and isotopic tools, he and his Tanzanian and Finnish associates could identify the pathways of geoenvironment-induced endemicity of diseases, such as fluorosis, stomach cancer and goitre.

After returning to India, he got instituted the Mahadevan International Centre for Water Resources Management of which he has been the Founder and Honorary Director.

Like ICTP, the Mahadevan Centre offers a series of customised courses for the water scientists, technologists and managers from the developing countries.

Aswathanarayana served as general secretary, Geological Society of India (1976–1979), Chairman, Working Group on Isotope Geochemistry of IAGC(1979–1983),[8] Leader, IAVCEI W.G.

on Deccan Volcanism (1979–83) and Chairman of the Working Group on "Geochemical Training in Developing Countries" of the International Association of Geochemistry and Cosmochemistry (1996–2008).

[11] The Geological Society of India, Bangalore, has brought out his popular science booklet, "Natural Resources and Environment", (2003) which has been translated into Indian languages.