Abstract Research on career adaptability has found that it helps people adapt at work. However, in modern uncertain and dynamic work environment, people need to perform proactive work behaviour to ensure individual effectiveness. Thus, to understand how career adaptability advances career development, it is necessary to examine its influences on proactive work behaviour. Adopting a relational perceptive, the current paper proposed leader‐member exchange and perceived coworker support as the mediators and future work self salience as a moderator. Data were collected with a three‐wave design in China. Findings largely supported the propositions, albeit showing partial mediation effects. This study extends existing understandings of the role of career adaptability at work, provides a new perspective about why it influences work‐related outcomes and enriches the knowledge about the antecedents of proactive work behaviour.