Ample evidence has been found for the association between affective, dyadic student-teacher relationships and students' engagement with schoolwork in Western, individualistic countries. There are far fewer studies, however, examining this association in Eastern, collectivistic countries. As maintaining harmony in interpersonal relationships plays a crucial role in collectivistic countries, student-teacher relationships may even be more important in collectivistic countries than in individualistic countries. In the present study, we therefore investigated cross-cultural differences in the strength of associations between student-teacher relationship quality and students' engagement based on data from the Netherlands (a Western country) and China (an Eastern country). The Dutch sample included 789 students (51.1% girls) and the Chinese sample included 588 students (52.9% girls) from grades 3 to 6 of elementary school. Students reported about the quality of their relationship with their teacher (closeness, conflict) and their behavioral and emotional engagement with schoolwork. Hierarchical linear modeling showed that the positive association between closeness and both behavioral and emotional engagement was stronger for the Chinese sample than for the Dutch sample. In contrast, the negative association between conflict and both behavioral and emotional engagement did not differ across countries. To conclude, closeness may be more relevant for Chinese students' engagement than would be expected based on Western studies, whereas conflict seems to be equally harmful in both cultures. Therefore, developing relationship-focused interventions for Chinese teachers and students seems important, either by adapting Western programs or by developing new programs especially designed for Chinese schools.