Reemployment of middle-aged and older adults is important and meaningful in helping them successfully transition and adapt to late adulthood. This study explored the lifelong learning experiences of successfully re-employed middle-aged and older adults in Taiwan. Semi-structured, in-depth interviews were conducted with 20 middle-aged and older adults to understand their reasons for reemployment, their learning experiences, and the benefits of re-entry into the workplace. The results revealed that middle-aged adults, especially women, interrupted their careers for family reasons. They chose to restart their careers after achieving family goals and for financial reasons. Lifelong learning is the key to restarting a professional career, including formal, informal, and non-formal learning activities. This study provides ways to assist middle-aged adults to re-enter the workforce or change careers, improve their confidence and competitiveness, gain recognition, and expand career prospects. The findings can be used as a reference for employment services to help middle-aged adults re-enter the workforce and for government and related agencies to design re-employment policies for middle-aged adults.