Using the quasi-experimental design, this study examined the effect of autonomy support on self-determined motivation in elementary school physical education (PE) students. One hundred and twenty six participants were assigned to either the autonomy support group (n = 61) or the control group (n = 65) for a six-week intervention period. Perceived teacher autonomy, perceived autonomy in PE, and self-determined motivation in PE were pre- and post-tested using validated questionnaires. Significant increases in perceived teacher autonomy and perceived autonomy in PE were observed in the autonomy support group, but not in the control group. Intrinsic motivation was higher in the autonomy support group than that in the control group. From an experimental perspective, these findings suggest that the autonomy support was successfully manipulated in the PE classes, which in turn increased the students’ perceived autonomy and intrinsic motivation.

• The SDT is a relevant theoretical framework for elementary school physical education.

• Using the quasi-experimental research design, this study is one of the earlies studies supporting that elementary school PE teachers can manipulate the instructional context using the SDT to increase students’ perceived autonomy and intrinsic motivation.

• Increasing students’ perceived autonomy may not lead to significant changes in other SDT constructs (i.e., amotivation, external regulation, introjected regulation, and identified regulation).