This study aims to discuss what masterity is found by investigating career competencies in working women’s work and life. Qualitative data from seven mid-aged women with more than 10 years of diverse work experiences were collected through in-depth semi-structured interview. The collected data was analyzed with career competencies for understanding how mid-aged women work and live. As a result, we found three categories such as “self-expression through work” as knowing why, “a holistic growth through work-life intersection” as knowing how, and “relationships as a basis for value creation” as knowing whom. Working mid-aged women freely crafted their career competencies in a context of their work and non-work, which ultimately show masterity leading to meaningful lives. Masterity found from this study can be explained for women’s sustainable career development. It is also expected to be a cornerstone of studying women’s masterity, as an alternative for the gender-blind discussion of the existing concept of masterity(Chang, 2015, 2018).