Introduction. The personality traits required of teachers and the challenges they face in achieving professional fulfilment have made it necessary to search for new methodological approaches to studying the functional structure of teachers' professional self-awareness. This involves examining the phenomenon from the perspective of systemics and the psychology of the subject. The purpose of the study is to substantiate the regulatory function of teachers’ professional self-awareness within the 'subject-person' system, adopting a system-subject approach. Materials and methods. The study of the regulatory function of a teachers’ professional self-awareness is based on the key principles of the system-subject approach, which states that the regulatory function of a person is specified through experiences that reflect self-attitude and attitudes towards others and events, while the regulatory function of a subject is specified through self-regulation, which is based on behavioral control. Theoretical methods were employed to substantiate its essence and content. These methods included the systematisation of results, an analytical discussion, a comparative synthesis, the concretisation of findings and the interpretation of scientific literature in accordance with the research problem. Research Results and Discussion. It was established that the regulatory function of the personal level of teachers’ professional self-awareness is realized through experience and manifests itself in an emotional and value-based attitude towards oneself as a professional, pedagogical work, and all participants in the educational process. The regulatory function of the subject level of professional self-awareness manifests itself in a teacher's ability to exercise cognitive, emotional, and volitional control over their behavior. It was revealed that cognitive control is a teacher's style-specific cognitive ability; emotional control is a teacher's ability to empathize and regulate emotional states; and volitional control is a teacher's ability to voluntarily organize their volitional efforts and control their pedagogical actions. Conclusions. It was proven that the regulatory function of teachers’ professional self-awareness can be described through the leading structural formations of the personality and the subject of pedagogical activity. The coordinated interaction of self-esteem and behavioral control subsystems determines the effectiveness of the regulatory function, which determines the directions of practical activities of psychological services in education in the design and implementation of programs aimed at creating optimal conditions for the self-realization of a teacher.