Aim/Purpose: This paper aims to evaluate the influence of an augmented reality mobile application on improving secondary students' visualization and comprehension of geometric concepts. Background: The study involved developing an AR app named Geometria to enhance geometry education. Methodology: In a specialized boarding school in Kokshetau, Kazakhstan, 82 tenth-graders were randomly split into control (n=42) and experimental groups (n=40), underwent either traditional instruction or lessons incorporating the AR Geometria app, and were subsequently assessed using a 20-question test spanning spatial relationships, 3D visualization, and advanced geometry concepts, complemented by a feedback questionnaire on the app's impact and usability, all under consistent teacher supervision. Contribution: The research serves as an exploration into the realm of AR in education, offering a detailed assessment of how the Geometria application can revolutionize traditional teaching methodologies in secondary geometry education. Findings: Upon analysis, the experimental group demonstrated significant advancement in their geometry proficiency, especially in competencies like 3D visualization, suggesting that augmented reality tools like Geometria can substantially bridge the conceptual gaps often encountered in conventional teaching settings. Recommendations for Practitioners: Teacher training on augmented reality should be provided, equitable student access should be ensured, and ongoing feedback should be gathered. Recommendations for Researchers: Larger, longer-term studies across diverse educational settings and technologies should be conducted. Impact on Society: Geometry instruction can be strengthened through the effective use of augmented reality to improve STEM outcomes. Future Research: Future studies should focus on best practices for augmented reality implementation and comparisons to other technologies.