Youth populations represent a key population for addressing mental health, yet many youths express reluctance towards help seeking. Considering the volume of time that almost all youth spend at school during the school year, it is important to assess the role of the school environment in relation to students’ attitudes toward help-seeking. Data from 47,290 grade 9 to 12 students and 116 Canadian secondary schools that participated in the 2018-19 wave of the COMPASS (Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, Sedentary behaviour) study were analyzed using GEE models to assess the student and school characteristics associated with attitudes regarding seeking help for mental health concerns from an adult at school. Overall, 58% of students reported being reluctant to seek help for mental health concerns at school. Students who reported lower self-rated mental health (aOR = 1.76, 95% CI = 1.65, 1.87), emotion regulation (aOR = 1.08, 95% CI = 1.07, 1.09), family support (aOR = 2.31, 95% CI = 2.16, 2.47), peer support (aOR = 1.20, 95% CI = 1.13, 1.31), and school connectedness (aOR = 0.93, 95% CI = 0.92, 0.93) scores were more likely to be reluctant towards help-seeking at school than students with more favourable scores on these variables. Students with higher flourishing scores were less likely than students who were languishing to report reluctance to help-seeking at school (aOR = 0.96, 95% CI = 0.96, 0.97). Students attending schools in areas with lower population densities and median household incomes between $50,000–75,000 were less likely to be reluctant to help-seeking relative to students attending schools in areas with higher density (aOR = 0.85, 95% CI = 0.79, 0.93) and median household incomes (aOR = 1.20, 95% CI = 1.13, 1.31), respectively. The availability of school mental health services and specialists were not associated with student help-seeking reluctance. High levels of resistance towards help-seeking among youth remain a significant barrier, particularly among youth at highest risk (i.e., with lower support and poorer mental health). The student and school characteristics identified in the current study can help inform strategies to promote greater acceptance of help seeking among students in schools.