The aim of the present article was to develop and validate a competency-based curriculum model for the education of biology teachers. The research method was a mixed approach, including both qualitative and quantitative phases. The statistical population in the qualitative phase included university instructors, school teachers, and exam preparation centers' educators in the city of Tabriz during the 2020-2021 academic year. In the quantitative phase, the population included biology instructors from universities in East Azerbaijan Province, school teachers, and exam preparation centers' educators in Tabriz during the 2021-2022 academic year. The sample size in the qualitative phase consisted of 15 individuals selected using the snowball sampling method until theoretical saturation was reached, while in the quantitative phase, 150 individuals were selected using a stratified proportional random sampling method. Data collection in the qualitative phase was conducted through semi-structured interviews, and in the quantitative phase, through a researcher-made questionnaire. To assess the validity of the qualitative phase's questionnaire, internal validity was used, and for reliability, test-retest reliability was employed. For the quantitative phase's questionnaire, content and construct validity were assessed, and Cronbach's alpha was used to measure reliability. Qualitative data were analyzed using "thematic analysis," while quantitative data were analyzed using "exploratory factor analysis." In the qualitative phase, out of the initial 310 codes, 44 categorized codes, 10 sub-themes, and 4 main themes related to competency-based curriculum elements—including objectives, content, teaching-learning activities, and evaluation—were identified, and the proposed model was designed. In the quantitative phase, construct validity and factor loadings of the identified components were performed using exploratory factor analysis, and ultimately, the competency-based curriculum model for biology teacher education was validated and confirmed. Therefore, the localized tool is applicable for the education of biology teachers.