The contemporary digital transformation of education necessitates the improvement of teacher training to prepare teaching professionals capable of effectively using digital technologies in the educational process. This issue is particularly relevant to the preparation of future biology teachers, as the content of biology education involves the active use of visualization, interactive resources, virtual laboratories, digital modeling, online platforms, and modern communication tools. The aim of the study is to provide a scientific and theoretical rationale for, and experimentally validate, a methodology for developing the digital competencies of future biology teachers through a massive open online course. As part of the study, a massive open online course entitled “Methods and Technologies of Teaching Biology” was developed and implemented in the educational process and hosted on the Stepik platform. The experimental study was conducted at Abai Kazakh National Pedagogical University and included ascertaining, formative, and control stages. The study involved 100 fourth-year students enrolled in the 6B01513 “Biology” educational program. Assessment was conducted using the TDC (Teachers' Digital Competencies) questionnaire developed by Javier Touron, consisting of 54 questions and a seven-point Likert scale. Five components of digital competence were assessed: information literacy and data processing; communication and collaboration; digital content creation; legal safety; and problem solving. Statistical analysis was performed using SPSS 26.0 and the non-parametric Wilcoxon test. The results demonstrated statistically significant changes across all the components examined. The greatest positive changes were observed in digital content creation, problem solving, communication, and collaboration. The findings indicate that a massive open online course can be used as an effective tool for the purposeful development of digital competencies among future biology teachers.