Background and context: Women remain underrepresented in cybersecurity despite growing global demand for skilled professionals. Outreach is widely used to build awareness, confidence, and interest in cybersecurity pathways, yet evidence about effective program design, inclusivity, sustainability, and longer-term impact remains fragmented. Objective: This systematic literature review (SLR) examines cybersecurity outreach initiatives, with a primary focus on interventions intended to increase participation among female high school students. Method: Guided by the PRISMA framework, the review synthesised literature published between 2014 and 2024. The primary focus was female high school students; because cybersecurity-specific evidence for this population was limited, gender-neutral cybersecurity and broader school-based STEM outreach were also included where findings offered transferable design insights. In total, 80 sources were included: 74 studies and 6 reports. Findings: Workshops and camps were the dominant delivery formats, while cybersecurity-specific programs remained comparatively limited and were largely technical in focus. Only seven cybersecurity outreach programs explicitly targeted female students. Longitudinal or semi-longitudinal evaluation was uncommon, and reporting on sustainability, gender-disaggregated outcomes, and post-program continuation was limited. The review synthesises these findings into a taxonomy of outreach program design characteristics. Implications: The findings provide an evidence-informed basis for designing more accessible, gender-responsive, sustainable, and evaluable cybersecurity outreach, and offers actionable recommendations for researchers, educators, and policymakers in tertiary education seeking to design outreach that creates inclusive pathways for female students into cybersecurity.