The purpose of this study was to determine the effect of the Van Hiele instructional model on students’ achievement in Circle Geometry at Daffiama Senior High School in the Daffiama-Bussie-Issa District of the Upper West Region in Ghana. The purposive and simple random sampling techniques were employed to select a sample of 75 participants for the study. The sample involved two groups: the experimental group and the control group. While teaching based on the Van Hiele model was carried out in the experimental group, teaching with the traditional method was carried out in the control group. The study employed a quasi-experimental research design. The instruments used for data collection were tests, interviews, and classroom observation. Findings from the data analysis suggested that participants were at the prerecognition level before the intervention, improved from the prerecognition level to level 2 after the intervention as the model facilitated learning. It was recommended that teachers determine the geometric thinking levels of students before instruction; the Van Hiele learning and instructional model is adopted in curriculum design and applied in the teaching of geometry and other areas of mathematics.