This research aims to develop mathematics learning tools based on Education for Sustainable Development (ESD) using the Outdoor Learning Mathematics method with the goal of enhancing mathematical connections of junior high school students in statistics. The research method employed is a mixed-methods approach combining qualitative and quantitative methods, both conducted through developmental research comprising planning, development, and evaluation stages. The sample for this research was two classes at SMPN 1 Tempeh with homogeneous mathematical abilities, where one class will be used as the experimental group and one class as the control group. Determining the research area using a purposive area sampling technique with the consideration that learning using the outdoor learning mathematics method with educational sustainable development (ESD) based learning tools has never been implemented at SMPN 1 Tempeh. The selection of eighth-grade classes is based on the consideration that statistics material is currently being taught in eighth grade, and eighth-grade students have not been subjects of research for similar studies before. The learning tools developed are designed in accordance with ESD principles and utilize outdoor mathematics learning approaches to enhance students’ understanding and skills in statistics. The results from Hypothesis Testing for Pretest indicate that a p-value of 0.648 is obtained, where this value > 0.05 means H0 is accepted and H1 is rejected. Therefore, it can be concluded that there is no difference in the mean between the control and experimental groups in the pretest. Whereas the result of Posttest Hypothesis Test indicate that a p-value of 0.028 is obtained, where this value < 0.05 means H0 is rejected and H1 is accepted. So the use of ESD-based mathematics learning tools with the Outdoor Learning Mathematics method is effective in improving students’ mathematical connections in statistics. The implication of this research underscores the importance of integrating mathematics education with sustainable development principles to reinforce students’ understanding and skills in mathematics while also fostering awareness of environmental and social issues.