The purpose of this study is to ascertain how students' self-efficacy, belief perceptions, and attitudes toward technology have changed as a result of mobile application-based instruction during the distance education era. Pre-test, post-test controls were used in the study's quasi-experimental research design. Students in the seventh grade from a public secondary school in Central Anatolia participated in the study. In the study, the students were given the Self-Efficacy Scale for Geometry, the Belief Scale for Geometry, and the Attitude Scale for Technology. T-tests for independent samples and t-tests for dependent samples were used to assess data from measuring tools. The study's findings revealed a substantial difference between the experimental and control groups' students' attitudes toward technology, ideas about geometry, and self-efficacy in those areas. The usage of various mobile applications in mathematics instruction has been recommended in light of the results found.