Robinson began his teaching career at what was then the Tamil Nadu Theological College in 1962. In 1987, Robinson accepted an invitation from the Predigerseminar at Soest, Germany to teach there. Later that year, however, the Principal of the United Theological College in Bengaluru, India, Rev. Dr. E. C. John, retired, and the school formed a committee to find a replacement. Robinson accepted their invitation to return to India and become Principal there, and also headed their Department of Old Testament studies. Professor Gnana has been invited to other institutions as well, where he taught for shorter periods of time. He was Visiting Professor at the University of Hamburg in 1982, and also taught at the St. Andrew's Theological College in the West Indies that same year. He taught at the Andover Newton Theological School in Massachusetts in 1983 as well as at the Lincoln Theological College in the United Kingdom.
Honours
While serving as the Principal of UTC, Bengaluru, friends of the Professor brought out a 377-page festschrift in his honour edited by his junior colleague Rev. Dr. D. Jones Muthunayagam entitled Bible Speaks Today: Essays in honour of Gnana Robinson, ISPCK, 2000,
The Senate of Serampore College, West Bengal, the first University in India with degree-granting authority elected Gnana Robinson as its President in 1986. He was preceded by Rev. Dr. C. D. Jathanna. Rev. Gnana continued as its President till 1988 and was succeeded by Dr. Jacob Verghis. Again in the year 1997, Rev. Gnana was elected as the President and was later succeeded by Rev. Dr. J. W. Gladstone in the year 2000. Dr. Robinson has been acknowledged to have provided leadership to the Senate which has over fifty theological colleges from South Asia affiliated to it.
Retirement
After retiring as the Principal of the UTC, Bengaluru, Prof. Gnana was invited by the Lutheran Theological Seminary in Philadelphia where he was Visiting Professor until 2001. He later returned to India and lives in Tamil Nadu and is extensively involved in developmental activities.
Development initiatives
For Rev. Robinson, theology did not mean existence within the seminary walls. He founded many development initiatives in Tamil Nadu. Prof. Gnana, as Principal of UTC, Bengaluru commissioned a team of volunteers along with the Ramakrishna Mission, Bengaluru to provide relief to the earthquake-affected people in Latur, Maharashtra. Rev. Gnana founded the Peace Trust, Kanyakumari. He also is a member on the following societies:
Bullock cart Workers' Development Association,
Peoples Association for Social Action,
Center for Rural Education and Employment for Development.