Research based in self-determination theory has demonstrated the importance of social agents for motivational processes in school-based physical education (PE). To focus more closely on the relational processes that underpin students’ motivation in PE, there have been calls for researchers to explore the specific teacher behaviors that facilitate students’ relatedness in PE. Our aim was to test a higher-order measurement model comprising distinct relatedness-supportive teacher behaviors, and to explore the ways in which students’ perceptions about their teacher directly and/or indirectly predict relatedness need satisfaction and motivation in PE. To test our higher-order model (Study 1), 656 high-school PE students reported the extent to which their teachers engaged in relatedness-supportive behaviors. In Study 2, 570 high-school PE students reported their motivational regulations for PE, as well as the extent to which their teacher engaged in relatedness-supportive behaviors, and satisfied their need for relatedness. We found support for the higher-order relatedness support model, and observed predictive pathways that were consistent with theory. Students reported satisfaction of their need for relatedness when they felt relatedness support from their teachers (β = 0.52, p < 0.001) and relatedness need satisfaction was in turn positively related to intrinsic (β = 0.51, p < 0.001), identified (β = 0.49, p < 0.001), and introjected (β = 0.25, p < 0.001) regulations for PE. These findings demonstrate the importance of relatedness-supportive teaching in PE, and implications of these data are discussed.