Adolescents are particularly vulnerable to poor sexual health outcomes such as sexually transmitted diseases, sexually transmitted infections, human immunodeficiency virus, and unintended pregnancy. While school-based sexual health education (SBSHE) can address adolescents' needs, they are often insufficient. Hence, their perception of SBSHE should be explored to improve current education. This review aims to consolidate the available evidence on perceptions, experiences, and needs of adolescents about SBSHE. Six electronic databases were searched from their inception date till June 2022. The included studies were assessed using the method of the Critical Appraisal Skills Program tool, and findings were meta-synthesized using Sandelowski and Barroso (2007). This review was registered via the International Prospective Register of Systematic Reviews. Overall, 51 studies were included, and three themes were identified: (1) teachings of SBSHE and its impact, (2) adolescents' preferred approach to SBSHE, and (3) importance of engaging and safe SBSHE. In conclusion, adolescents had mixed reactions toward SBSHE. They expressed the need for inclusivity (gender identity and racial, ethnic, and cultural groups). Having a "safe space," well-trained educators, and interactive approaches were important and hence should also be considered. More qualitative studies from different geographical regions are needed. Diverse topics (e.g., mutual consent, sexual abuse, and violence) should also be discussed. The use of multiple educators (e.g., schoolteachers, specialist teachers, and peers) should also be deliberated in future SBSHE research. Findings from this review should be triangulated by evaluating the perceptions of various stakeholders (e.g., educators, adolescents, and SBSHE administrators).