Career landscapes have changed over the recent decades with a de-standardization of career paths. Globalization, more flexible labor markets, and new ways of working are just a few of the many factors that erode the boundaries of a well-defined career path. Today, many workers are thus confronted by the vulnerability paradox, where diverse career opportunities and an emphasis on personal agency carry a share of uncertainty, inequity, and pressure to keep fit at all times. This chapter discusses the idea of sustainable careers as an antipode to occupational vulnerabilities in the modern world of work. Indeed, promoting sustainability in flexible and deregulated labor markets can be very difficult. However, this sustainability is necessary to promote employees’ well-being. To elaborate these crucial challenges, we will develop an integrative theoretical approach encompassing both micro- and macro-level factors that may influence occupational trajectories and workplace experiences.