Gupta started his career as an associate professor at the Birla Institute of Technology and Science, Pilani, Rajasthan. He quit teaching and decided to be an Entrepreneur as he was "not able to implement ideas into practice". he came to Bombay (now Mumbai) and worked in a small British pharmaceutical Manufacturing company. He founded Lupin in 1968 with a start-up capital of ₹ 5000 borrowing the money from his wife. The first office of Lupin was rented premises in Central Mumbai used for dispatching medicines. Later, with a loan from Central Bank of India of ₹ 8 lakh, it started a factory whose major order was to provide iron and folic acid tablets to the Government of India programmes related to mother and child Health care. Under his leadership, Lupin became a global pharmaceutical company whose consolidated turnover was ₹110,866 million (equivalent to ₹130 billion or US$1.9 billion in 2017) and profit after tax was ₹18,364 million (equivalent to ₹21 billion or US$320 million in 2017) at the end of March 2014.