He joined Raipur Mill as chairman in 1912. The operations of the mill had not yet stabilized; hence, Kasturbhai had to take care of operations closely. He started off as a timekeeper in the mill, but fed up with the repetitive nature of the job, he started working with suppliers of the mill and traveled far and wide to understand the supplier market. The boom in demand during and post-
World War I helped him in stabilizing the operations of the firm. He joined the board of directors of Raipur mill in 1918. Later he established Ashoka Mills in the 1920s with the help of Dahyabhai Patel. Kasturbhai expanded his business with help of his mentor and trusted general manager of all his
textile mills, Dahyabhai Motilal Patel, who had the vision and insight to advise Kasturbhai to invest in or acquire five mills between 1924 and 1938, including four belonging to relatives. These include establishment of
Arvind Mills and Nutan Mills in 1931, Aruna Mills in 1928, Ahmedabad New Cotton Mills in 1938.
Swadeshi movement by
Mahatma Gandhi in the 1930s and starting of
World War II in 1939 helped textile industry in India. He modernised all seven mills. They had 12% of India's total spinning capacity and 24% of Ahmedabad's total weaving capacity resulting in they were seventh largest cotton consumer in 1939 in India. In 1948, his business group was named in the list of business houses indulging in black-marketing.
R. K. Shanmukham Chetty, the finance minister and a friend of Kasturbhai had to resign for reportedly suggesting that its name be dropped from the list. The Income Tax department followed its allegations with a spate of inquiries and after almost ten years, absolved the group of any wrongdoing. In 1952, his trusted advisor and general manager, Dahyabhai Motilal Patel, helped strategise and found
Atul Limited (literally, 'incomparable'), India's first modern dyestuff manufacturer, in collaboration with
American Cyanamid Company. It was inaugurated by the first prime minister,
Jawaharlal Nehru. ==Politics==