The modernization of pedagogical education for coaches and supplementary education teachers in sports is crucial to enhance their professional knowledge, skills, and abilities. Purpose: This study aims to enhance the efficacy of professional competency development among teachers of supplementary education in recreational swimming for infants under the age of one year. It aims to develop and validate a professional support technology tailored for such specialists in early swimming centers. Materials and methods: The research involved 18 teachers (aged between 22 to 45 years) of supplementary education in recreational swimming for infants, with their professional experience ranging from one to twenty years. All professionals possessed a higher education in physical education. The teachers were divided into a control group (CG, n=9) and an experimental group (EG, n=9). The improvement of professional competencies in the CG was conducted in accordance with the guidelines outlined in the state professional standard for "Supplementary Education Teacher for Children and Adults. "In EG the professional improvement was carried out according to the developed technology of professional support for teachers. With the help of the developed questionnaire the diagnosis of the state of formation of professional competences of teachers and the evaluation of their activity in accordance with the professional standard for this profession were carried out. Results. At the beginning of the research a low level of theoretical knowledge among the teachers of supplementary education in swimming for children was found. Most of the teachers were classified in the "low" and "medium" levels of professional competence formation. The teachers' work functions did not meet the professional standards for this category of specialists. At the end of the research an increase in the values of the indicators of the level of knowledge was noted in the experimental group, which was 5 times higher than this indicator in the control group. Most of the teachers in the experimental group rated their level of competence compliance as "high" in all work functions. In the control group, teachers rated their level as "average" at the end of the research. Conclusions. The obtained positive results of the testing of the proposed pedagogical technology for the improvement of the professional competences of teachers of children's swimming supplementary education can be used in other institutions of supplementary education.