Introduction: The counselors’ professional development seeks education and skills training, experience, and expertise, not only in one field but for the present and the future. Aim: The present research was conducted to design and study the psychometric properties of the “Counselors’ Professional Development Scale". Method: The current research was a mixed exploratory design and tool making. The statistical population of this research included all counselors of counseling and psychology centers in Tehran in 2022. The number of samples reached 12 semi-structured interviews, which were selected by purposive sampling. Construct validity and Cronbach's alpha coefficient were used to examine the psychometric properties of the Counselors' Professional Development Scale. Results: The results of the present study showed that the Counselors’ Professional Development Scale has Cronbach's alpha reliability and adequate construct validity in a sample including counselors of counseling and psychology centers in Tehran. Conclusion: The Counselors’ Professional Development Scale in the theoretical framework of 6 selected codes based on the grounded theory was designed and the results indicate the desired reliability and validity of the present tool. It is suggested that the authorities of higher education and the organization of the psychology and counseling system consider the designed tool and provide a suitable platform for the professional development of counselors.