Background: Pregnancy is a time of increased risk for developing or re-experiencing mental illness. Perinatal mental health screening for all women is recommended in many national guidelines but a number of systems-level and individual barriers often hinder policy implementation. These barriers result in missed opportunities for detection and early intervention, and are likely to be experienced disproportionately by women from culturally and linguistically diverse backgrounds, including women of refugee backgrounds. The objectives of this study were to develop a theory-informed, evidence-based guide for introducing and integrating perinatal mental health screening across health settings; and to synthesise the learnings from an implementation initiative and multi-sectoral partnership between the Centre of Perinatal Excellence (COPE), and a university-based research centre. COPE is a peak body in perinatal mental health and Non-Governmental Organization commissioned to update the Australian national perinatal mental health guidelines, train health professionals and rollout innovative digital screening across healthcare settings. Methods: In this case study, barriers to implementation were prospectively identified and strategies to overcome them were developed. A pilot perinatal screening program with a strong health equity focus was implemented and evaluated at a large public maternity service delivering care to a culturally diverse population of women in metropolitan Melbourne, Australia, including women of refugee background. Strategies identified pre-implementation and post-evaluation were mapped to theoretical frameworks. An implementation guide was developed to support future policy, planning and decision-making by healthcare organisations. Results: Using a behavioural change framework (COM-B), the key barriers, processes, and outcomes are described for a real-world example designed to maximise accessibility, feasibility, and acceptability. A program logic model was developed to demonstrate the relationships of the inputs, which included stakeholder consultation, resource development, and a digital screening platform, with the outcomes of the program. A seven-stage implementation guide is presented for use in a range of healthcare settings. Conclusions: These findings describe an equity-informed, evidence-based approach that can be used by healthcare organisations to address common systems and individual level barriers to implement perinatal mental health screening guidelines.