Studies have shown that the School Kindness Scale (SKS) has adequate psychometric properties in different societies such as Canada, Turkey, and the Philippines. However, there is scarce evidence on the psychometric validity of this scale across multiple societies and educational contexts. This study explores the cross-national invariance of the SKS among high school students in the Philippines, Hong Kong, and mainland China. Results showed that the modified unidimensional model of school kindness with correlated error terms on item number 2 and 3 had the most optimal fit. There was evidence supporting partial invariance of the modified unidimensional model of school kindness across setting and year level, and full invariance across gender. Whereas school kindness also demonstrated positive correlations with perceived academic performance in Hong Kong and mainland China, this construct was linked to higher emotional and social engagement in math in all contexts.