Professional identity is fundamental to counselors' competence and the quality of school counseling services, yet empirical evidence on certified school counselors in developing countries remains limited. This study examined the professional identity of certified Indonesian school counselors and its variation across selected sociodemographic characteristics, particularly educational background. A cross-sectional survey was conducted with 588 certified school counselors selected through convenience sampling from approximately 1,200 participants who attended the 2025 National School Counseling Competency Development Training Program organized by the Ministry of Primary and Secondary Education of the Republic of Indonesia, representing primary, junior secondary, and senior secondary schools across Indonesia. Data were collected using the Professional Identity Scale for Indonesian School Counselors, developed through a synthesis of the theoretical perspectives of Puglia, Emerson, CACREP, and Woo et al. The instrument measures four dimensions: philosophical understanding and professional beliefs, professional knowledge, professional roles and expertise, and professional pride. Content validity was established through the Delphi technique, Aiken's V, and item discrimination analysis. Data were analyzed using descriptive statistics, independent samples t-test, and Welch's ANOVA. The findings showed that certified school counselors generally remained at the transition stage of professional identity (M = 3.46). Significant differences were found across gender, age, educational qualification, employment status, professional experience, certification pathway, school level, and educational background, whereas regional differences were not significant. Counselors with discipline-specific education in guidance and counseling demonstrated stronger professional identity, highlighting the need to integrate identity development into pre-service education and differentiated continuing professional development. The findings highlight the need for differentiated professional identity development programs for school counselors in both academic and professional education.