This study investigated the effect of situated learning environment in enhancing mathematical reasoning and proof among tenth grade students. To achieve the aim of the study, a pre-posttest of mathematical reasoning and proof was used, and its validity and reliability were verified. The sample of the study consisted of 50 female students who were distributed equally into two groups; the experimental who were taught the circle unit in geometry by situated learning environment, and the control group who were taught by the traditional method. The results indicate a significant improvement in the students' ability of reasoning and proof in favor of the experimental group. Moreover, a diversity of mathematical reasoning and proof strategies were used by the experimental group.