Being well-connected to the political elite of West Bengal through his relationship with B.C. Roy and with P.N. Haksar, Nagchaudhuri was nominated to serve as the Chairman of the Cabinet Committee of Science & Technology from 1969 to 1972. During this period, he also served as the Scientific Advisor to the Ministry of Defence (MoD). He became a Member of the Planning Commission in 1970. From 1970 to 1974, he served as the Scientific Advisor to the DRDO.