Peer teaching is recognized as a powerful instructional method; however, there is a paucity of studies that have evaluated the outcomes experienced by peer-teachers and their student recipients in the context of trained, non-reciprocal, high school physical education (PE). Accordingly, the effectiveness of a formalized and trained non-reciprocal peer teaching (T-PT) program upon psychosocial, behavioral, pedagogical, and student learning outcomes within high school PE classes was investigated. Students from eight intact classes (106 males, 94 females, Mage = 12.46, SD = 0.59) were randomly assigned to either a T-PT intervention group (taught by a volunteer peer-teacher who was trained in line with a tactical games approach) or untrained group (U-PT; where volunteer peer-teachers received no formal training, but did receive guidance on the game concepts to teach). Data were collected over 10 lessons in a 5-week soccer unit. Mixed-model ANOVAs/MANOVAs revealed that, in comparison to U-PT, the T-PT program significantly enhanced in-game performance actions and academic learning time among student recipients. Those in the T-PT also provided greater levels of feedback and structured learning time, as well as reporting more positive feelings about peer teaching and fewer perceived barriers to accessing learning outcomes. These findings show that non-reciprocal peer-teachers who receive formalized support through training and tactical games approach-based teaching resources can enhance behavioral, pedagogical, and motor performance outcomes in PE.