Due to increased dynamics in the world of work and the resulting responsibility of individuals to shape their careers more independently, there is an increased need to focus on the individual as an active agent in the development of a successful career. Drawing on action regulation theory, this four-wave longitudinal study investigates the dynamic relations between protean career orientation, engagement in career self-management behaviors, and subjective career success over time. Based on a sample of N = 574 German employees, we tested a random intercept cross-lagged panel model (RI-CLPM) to focus on within-person dynamics across four time-points while accounting for stable between-person differences. We found partial support for assumed dynamics in these variables, in that increases in protean career orientation predicted subsequent increases in career self-management behaviors. Moreover, increased protean career orientation and subjective career success (but not career self-management behaviors) predicted further increases in the same respective states. However, increases in career behaviors did not predict increases in subjective career success and increases in subjective career success did not predict increases in protean career orientation or career self-management behaviors. We discuss the findings in light of adopting a dynamic within-person approach to understand key career development constructs.