There has been much debate over the micro-level relationship between employment situations and fertility in Europe and Northern America. However, related research in East Asia is scant, although countries in this region have some of the lowest fertility rates in the world. Moreover, most studies analyse the employment–fertility relationship from a static perspective and only for women, which underemphasises life course dynamics and gender heterogeneity of employment careers and their fertility implications. Drawing on retrospective data from the 2017 Taiwan Social Change Survey (TSCS), this study explores women’s and men’s career trajectories between ages 18 and 40 in Taiwan using sequence cluster analyses. It also examines how career variations associate with different timing and quantum of birth. Empirical results show that economically inactive women experience faster motherhood transitions and have more children by age 40 than women with stable full-time careers. For men, having an unstable career associates with slower fatherhood transitions and a lower number of children. For both genders, self-employed people are the earliest in parenthood transitions and have the highest number of children by midlife. Our findings demonstrate sharp gender contrasts in employment careers and their diversified fertility implications in low-fertility Taiwan.