Today's society, shaped by demographic changes and a global economy, has created different employment trends and work lives that result in adults' engaging in postretirement second careers. This phenomenon is a common occurrence in rapidly aging societies like Korea. This qualitative study examined the postretirement career transition process of Korean middle-aged adults. In-depth interviews were held with nine individuals ranging from 48 to 65 years identified as postretirement workers following voluntary retirement from private and public sectors. Data analysis revealed four phases in the career transition process: experiencing disequilibrium in a previous career, reflecting on self and context, making new professional connections and changes, and committing to new careers. The career transition was also a process involving different modes of learning, leading to the conclusion that the career transition process is essentially a learning process in which individuals acquire new perspectives and meaning in a new role.