We implemented GeoGebra software in Rwandan secondary schools to check its effectiveness during teaching and learning geometry concepts. The quasi-experimental design was used, and four schools were purposefully selected. Two schools were from Northern Province, while the other two were selected from Kigali city. A geometry-based test composed of 15 open questions was designed to assess the teaching effect before and after learning geometry. The study was conducted from December 2020 through June 2021 with 87 students. Two schools were assigned as control while the other two as experimental groups. Each group comprised one school from Kigali and one from Northern Province. We analyzed data using SPSS and computed multivariate analysis of variance. We found that students who learned with GeoGebra outperformed those who learned without GeoGebra (M = 77.68% and SD = 14.13 versus M = 56.78% and SD = 15.77, with p < 0.001 and d = 0.254). We also found that the number of students who were able to perform each of the 15 questions increased drastically due to the potential of GeoGebra. The study recommends the use of GeoGebra in all teaching and learning activities of mathematics.