Mental health education is a central part of school nurses' practice. Mental health literacy is an asset for health that educational initiatives can strengthen, and a significant determinant of mental health. This study was intended to examine the relationship between positive mental health literacy (PMeHL) and mental well-being to discuss its implications for school health services' mental health education. The relationship was assessed using a multiple linear regression model controlling for relevant covariates. Data were derived from a cross-sectional school-based survey including 1,888 adolescents aged 15-21 years (response rate 97.3%). A weak gender difference was found in PMeHL. The regression model accounted for 41% of the variance in adolescents' mental well-being; PMeHL was a significant explanatory variable of mental well-being. Accordingly, the current study found support for including PMeHL, or knowledge of how to obtain and maintain good mental health, as an integral component of school health services' mental health education among adolescents.