Objective: Resource constraints limit the use of evidence-based clinical guidelines (CPGs). This study describes the adaptation and scale-up of a context-specific maternity care pocket guide, initially co-created in Zanzibar, to five urban health facilities in Dar es Salaam, Tanzania. Design: Participatory, iterative co-creation. Settings: Five government health facilities in Dar es Salaam (2021). Population: Maternity care providers, researchers, women and other stakeholders. Methods: A structured, flexible CPG adaptation model was applied, combining a mixed-methods situational analysis, review of global and national CPGs, and iterative feedback via focus groups and individual reviews until saturation. The guide was then pilot-tested and implemented. Main Outcome Measures: Co-creation process, PartoMa Pocket Guide and implementation strategy. Results: Two review cycles with 54 frontline providers, two external reviews (11 international experts and 10 Dar es Salaam Health Management Team members), and two consultation meetings with a 28-member core team. The process produced a 24-page infographic pocket guide of CPGs, covering routine care and common complications during childbirth, and a dissemination strategy including in-house, low-dose, high-frequency training. Using the Zanzibar guide streamlined adaptation, revealing notable consistency across resource-constrained settings. However, the process remained time- and resource-intensive, particularly when international scientific evidence was insufficient or failed to capture urban clinical complexities. Conclusions The PartoMa CPG adaptation model effectively contextualises and scales evidence-based CPGs in high-volume, resource-constrained urban settings. Global CPG developers should integrate end-user needs from the outset for more practical and cost-effective adaptations. Funding: Danida Fellowship Centre (DFC), Ministry of Foreign Affairs of Denmark (DFC project no. 18-08-KU).