Over the last three decades, the professional landscape has changed, and career paths have become more plural, complex, and flexible, as well as less predictable. Consequently, career sustainability has become a major concern. Since the framework of sustainable careers captures the complexities of modern careers, we used it in the present study to understand how various types of significant life events (i.e., negative work events, negative nonwork events, positive work events, and positive nonwork events) hinder or foster career sustainability among 870 professionally active adults in Switzerland using a longitudinal design. We used repeated measures analysis of variance to study changes in health (i.e., self-rated health and stress at work), happiness (i.e., life satisfaction, quality of life, and job satisfaction), and productivity (i.e., employability and career prospects) by the type of significant life events over time, from 1 year before the event (T0) to 1 year after the event (T2). Results indicated that work events are important to consider when studying career sustainability as there is evidence for spillover effects from work to life. Specifically, experiencing positive work events seems to foster career sustainability, and these effects seem to be stronger than the negative effect of negative work or nonwork life events on health, happiness, and productivity.