Along with a large increase in the prevalence of Work-Family Conflict and Family-Work Conflict as a consequence of societal developments, research has outlined possible negative consequences of this development. Adding to these potential dangers, this study investigates the hypothesised negative effect of Work-Family Conflict and Family-Work Conflict on Career Self-Efficacy, which would be detrimental to individual careers. Two mediators, which are sub-dimensions of Eudaimonic Well-Being, are introduced to explain the relationship: Purpose in Career and Personal Growth at Work. To test the model, self-report questionnaires of the mentioned concepts were administered to a sample of Spanish employees (N = 327) at two time points, three months apart. Results were analysed using structural equation modelling in Jamovi, revealing Family-Work Conflict as a direct negative predictor of Career Self-Efficacy and Work-Family Conflict as an indirect negative predictor via Purpose in Career and Personal Growth at Work. With this research, the study contributes not only to the awareness of the negative consequences of Work-Family and Family-Work Conflict, but it also highlights the importance of Career Self-Efficacy and brings forth possible explanatory mechanisms for the outlined effects. In doing so, it responds to the growing societal need to protect employee well-being and career self-efficacy in the face of blurred work-life boundaries and changing career realities.