This research aims to reveal the effects of using augmented reality applications on seventh-grade secondary school students' academic achievement and motivation and to identify students' views on augmented reality applications. For this purpose, the augmented reality application called "CellAR" has been developed for the "Cell and Cell Division" unit. The study used pre-test - post-test control group quasi-experimental design research method and general survey model. During the research, the experimental group students used the CellAR augmented reality learning application developed by the researcher in addition to the regular course materials (textbooks, e-books, printed materials, videos, visuals, etc.). In contrast, the students in the control group used only the regular course materials. An academic achievement test, motivation scale, and opinion questionnaire for augmented reality application were used to collect data. T-test for independent samples, single-factor analysis of covariance (ANCOVA), and descriptive statistics were used. According to the results, the academic achievement and motivation of the students in the experimental group using augmented reality application were significantly higher than the students in the control group. According to descriptive results, the students thought that the augmented reality application helped them learn the subjects, facilitated the concretization of abstract concepts, and provided active learning experiences. Similarly, the students found the augmented reality application interesting and stated that it increased their creativity and motivation.