This study aimed to determine whether goal orientations were related to students’ self-reported misbehaviors in physical education and to examine whether the effects were mediated by moral disengagement. A two-study project employing structural equation modeling was conducted with high school students (Study 1, n = 287; Study 2, n = 296). In Study 1, the results showed that mastery-avoidance goals were unable to predict five misbehaviors (i.e., aggressive behavior, low engagement, failure to follow directions, poor self-management, and distracting behavior). Mastery-approach goals negatively predicted low engagement, failure to follow directions, and poor self-management. Performance-approach goals positively predicted aggressive and distracting behaviors, while performance-avoidance goals positively predicted all five misbehaviors. In Study 2, the results indicated that the positive relationships between performance-approach goals and misbehaviors and between performance-avoidance goals and misbehaviors were mediated by moral disengagement. These results are discussed in terms of the model of achievement goals, and implications for physical education are also highlighted.