George Thomas graduated in medicine from the Kilpauk Medical College, Chennai, India in 1983. While at college he was co-founder of the Medical Action Forum, a group which tried to engage mainstream medical professionals in social issues. The group became defunct when many of the core members migrated to the UK and the USA.

George continued to remain active in social issues through many groups floated for a single agenda, for example against the sale of human body parts in India, which resulted in the Human Organs Transplant Act. He also campaigned against nuclear weapons in India through the Coalition for Nuclear Disarmament and Peace (CNDP). He writes occasionally for The Economic and Political Weekly.