This study examines the relationships between proactive decision-making, perceived time poverty, and career sustainability within Kazakhstan’s evolving labor market. Guided by the Social Cognitive Model of Career Self-Management and Conservation of Resources theory, the research investigates how proactive career behaviors influence time poverty and sustainable career outcomes, while accounting for demographic differences. The study aims to assess whether proactive decision-making reduces time poverty and enhances career sustainability, and how these relationships vary by gender and age. Data were collected from a convenience sample of 400 employed adults in Kazakhstan using validated survey instruments on a six-point Likert scale. Structural equation modeling was used to test three core hypotheses: (1) proactive decision-making is negatively associated with time poverty, (2) proactive decision-making is positively associated with career sustainability, and (3) time poverty is negatively associated with career sustainability. Results supported all hypotheses. Proactive individuals reported less time poverty and greater career sustainability. Time poverty significantly undermined sustainable career development. Moderation analysis revealed that younger individuals and women were more susceptible to time poverty’s negative effects, while older adults and men demonstrated greater resilience. These findings underscore the need for targeted interventions to promote proactive career strategies and mitigate time-related barriers across demographic groups.