Objective To construct an online intervention program for career adaptability among junior nurses and verify its effectiveness, aiming to provide a reference for promoting career adaptability of junior nurses. Methods Based on the six core therapeutic processes of Acceptance and Commitment Therapy（ACT）, combined with literature research, previous research results, and Delphi expert consultation method, an intervention program was constructed.Eighty-two junior nurses were divided into a control group (n=41) and an intervention group (n=41) using a random number table; the control group received routine standardized nursing training, while the intervention group additionally implemented the ACT-based online intervention program for workplace adaptability for 8 weeks. Results After the intervention, the scores of career adaptability and psychological flexibility in the intervention group were significantly higher than those in the control group, and the scores of challenging and hindering stressors were significantly lower than those in the control group （all P＜0.05）. Conclusion The implementation of the ACT-based online intervention program is beneficial for improving the career adaptability and psychological flexibility of junior nurses, reducing their work stress, and thus promoting their career adaptation.