The aim of this study is to examine the impact of mathematical modeling activities using the history of mathematics on students' anxiety in geometry instruction. The study was conducted with 7th-grade students (n=30) studying in a public school during the first semester of the 2021-2022 academic year. In the research, nested mixed pattern from mixed research methods was used. Mathematical modeling activities based on the history of mathematics, designed by the researcher in accordance with the 7th-grade geometry curriculum, were implemented with the study group. Data were collected through written worksheets during the implementation process. Prior to and after the implementation process, a geometry anxiety scale was administered to the study group, and student opinions were obtained. The data obtained from the implementation were analyzed using content analysis. The research findings revealed a decrease in students' anxiety towards geometry and a positive change in students' perceptions of geometry.