Teacher-student relationships have been linked to autonomous motivation and achievement. However, relatively little is known about whether satisfying students' psychological needs mediates the association between teacher-student relationships and student happiness. Furthermore, this relationship needs to be examined in samples of students from different ethnic and racial backgrounds. In this structural equation modeling study (N = 1,961), we found that teacher-student relationships were positively and moderately associated with the satisfaction of psychological needs for autonomy, relatedness, and competence. Satisfying psychological needs, in turn, was moderately positively associated with happiness. These findings held across African American, Asian American, and Latinx subsamples. For the overall sample, students in higher grade levels perceived that their psychological needs were met to a lesser degree than students in earlier grades. However, only the Latinx subsample replicated this effect. Teacher-student relationships may promote happiness via meeting psychological needs.