Background: Mother-to-child transmission (MTCT) of HIV remains a major public health challenge in Nigeria, particularly in military health facilities where gaps in coordination, peer-support integration, and context-specific implementation hinder prevention of mother-to-child transmission (PMTCT) services.

Aim: To develop a systems-informed implementation framework for integrating a Mentor Mothers peer-support programme into PMTCT services in Nigerian military hospitals.

Method: A theory and framework development design was used, informed by an underpinning qualitative study and structured literature synthesis. Development followed three stages: establishing a starting point, constructing the framework, and describing it. Walker and Avant’s theory development approach guided concept integration, with stakeholder feedback enhancing contextual relevance.

Outcome: The framework includes four interrelated domains: governance and contextual inputs, Mentor Mothers’ capacity building, integrated clinical and psychosocial services, and community engagement. These domains aim to improve service uptake, retention in care, antiretroviral therapy adherence, and continuity of care through coordinated peer support and reproductive health integration.

Conclusion: The framework provides a structured, systems-based approach to strengthening PMTCT implementation in military healthcare settings.

Recommendation: Pilot testing with evaluation of reach, fidelity, acceptability, and effectiveness is recommended before wider implementation.