Yoshino spent his entire non-academic career at Asahi Kasei Corporation. Immediately after graduating with his masters degree in 1972, Yoshino began working at Asahi Kasei. He joined the Exploratory Research Team at Asahi Kasei Corporation in the early 1970s to explore new general-purpose materials, initially exploring practical applications for polyacetylene but turned to experimenting with using polyacetylene as an anode material once Japans electronics industry attempted to create new lightweight and compact rechargeable battery to power their mobile devices.
He began work in the Kawasaki Laboratory in 1982 and was promoted to manager of product development for ion batteries in 1992. In 1994, he became manager of technical development for the LIB manufacturer A&T Battery Corp., a joint venture company of Asahi Kasei and Toshiba. Asahi Kasei made him a fellow in 2003 and, in 2005, general manager of his own laboratory. Since 2017, he has been a professor at Meijo University and his status at Asahi Kasei has changed to honorary fellow.