Adolescent girls are an important target group for breast cancer education and promoting breast awareness. However, research has not established schoolgirls’ perceived importance of breast cancer education or explored factors that may impact engagement. This study aimed to identify schoolgirls’ concerns about breast cancer, desire to know more and perceived importance of breast cancer education, and explored associations with demographic factors. Of 2089 schoolgirls (11–18 years) surveyed, 1958 completed all relevant breast cancer questions and demographic factors (ethnicity, school type, breast size, physical activity level and age). χ2-Tests assessed associations between demographics, desire to know more and perceived importance of breast cancer. Overall, 44% of schoolgirls reported concerns about breast cancer, 72% wanted to know more and 77% rated the topic as extremely important. Breast size was not associated with wanting to know more about breast cancer. Schoolgirls who wanted to know more about breast cancer were White, from single-sex schools with boys at sixth form, more physically active and older. However, among other ethnic groups, school types and physical activity levels, the proportion of girls who wanted to know more about breast cancer was still high (≥61%). This study provides evidence of the need for breast cancer education for schoolgirls across all school types, irrespective of breast size or physical activity levels. The results highlight the need to be inclusive and engage schoolgirls from all ethnic groups and to promote breast awareness at a young age to ensure effective breast cancer education.