In 1956, Miller joined the rapidly growing Rhode Island-based conglomerate Textron, Inc as an assistant secretary. He became a Vice President of the company in 1957, CFO in 1958, and both the COO and company president in 1960. In the following years, Textron's sales boomed across a range of consumer goods, industrial equipment, and aerospace products. He became Textron's CEO in 1968 and retained that role following his 1974 election as chairman of Textron's board of directors. He held these posts until he joined to the Federal Reserve Board. Despite the economy's weakening state during his time as CEO, Textron's sales grew 65% to $2.8bn as the company operated 180 plants worldwide. This allowed the company's sales and net income to keep pace with the decade's accelerating inflation (albeit with a temporary dip in inflation-adjusted net income during the 1973-75 recession).