This study aimed to examine the teachers' humanistic role in terms of integrity, dignity, and freedom in online classes, and its effect on mathematics learning achievement. The cross-sectional survey design was carried out by taking 2260 students from school to tertiary levels in Nepal during the COVID-19 pandemic. T-test, ANOVA, and hierarchical regressions were the major statistical techniques used to yield the results in the research. The results showed that access to the internet, grades/levels, and availability of digital devices are significant in the practice of the humanistic role of teachers and students' learning achievement. Additionally, many factors such as teachers' equality and fair treatment, expression of negative emotions, and displaying energy and enthusiasm in teaching-learning activities, interest in students' well-being, extended moral support, positive attitude, and understanding of pressures and limitations of students are significant predictors in the achievement of mathematics.