This study aimed to examine the effectiveness of the TGfU (Teaching Games for Understanding) tactical-game approach in promoting metacognitive knowledge (declarative knowledge, procedural knowledge, conditional knowledge, information management), metacognitive regulation (planning, monitoring, problem solving strategies, evaluation, imagery) and game- play performance in physical education. An experimental intervention study in basketball was conducted with pre- and post- intervention measures. The participants were forty-one, seventh grade, students who came from two classes of a Senior High School from a rural area of Southern Greece. The classes were randomly labelled as experimental group (8 boys, 12 girls), which was taught basketball by the TGfU, or control group (10 boys, 11 girls), which was taught basketball by the technical skill-based approach. Both participating groups of students were taught ten lessons in respective ten weeks, each of which lasted forty-five minutes. Students’ metacognition was assessed pre- and post- intervention using self-report questionnaire, and their basketball game performance was estimated by two experts in both conditions. The main results showed that (a) after the completion of the intervention, the TGfU group of students, compared to technical teaching group of students, reported higher metacognition in perceptual knowledge, information management, conditional knowledge, problem solving strategies and evaluation, and performed better in games, and (b) in the post- vs pre- teaching condition, the technical teaching group only referred to higher using of declarative knowledge, whereas the TGfU teaching group achieved higher performance in games, and it referred to more frequent use of metacognitive knowledge of declarative, perceptual, information management and conditional, and of metacognitive regulation of planning, problem solving strategies and evaluation. Overall, the tactical-game approach of TGfU proved effective in improving both metacognition and performance in physical education classes. The results are discussed for their applications into effective learning and future research.