Background: Community-based strategies to test for HIV, hepatitis B virus (HBV), and sickle cell disease (SCD) have expanded opportunities to increase the proportion of pregnant women who are aware of their diagnosis. In order to use this information to implement evidence-based interventions, these results have to be available to skilled health providers at the point of delivery. Most electronic health platforms are dependent on the availability of reliable Internet connectivity and, thus, have limited use in many rural and resource-limited settings. Objective: Here we describe our work on the development and deployment of an integrated mHealth platform that is able to capture medical information, including test results, and encrypt it into a patient-held smartcard that can be read at the point of delivery without the need for an Internet connection. Methods: We engaged a team of implementation scientists, public health experts, and information technology specialists in a requirement-gathering process to inform the design of a prototype for a platform that uses smartcard technology, database deployment, and mobile phone app development. Key design decisions focused on usability, scalability, and security. Results: We successfully designed an integrated mHealth platform and deployed it in 4 health facilities across Benue State, Nigeria. We developed the Vitira Health platform to store test results of HIV, HBV, and SCD in a database, and securely encrypt the results on a Quick Response code embedded on a smartcard. We used a mobile app to read the contents on the smartcard without the need for Internet connectivity. Conclusions: Our findings indicate that it is possible to develop a patient-held smartcard and an mHealth platform that contains vital health information that can be read at the point of delivery using a mobile phone-based app without an Internet connection. Trial Registration: ClinicalTrials.gov NCT03027258; https://clinicaltrials.gov/ct2/show/NCT03027258 (Archived by WebCite at http://www.webcitation.org/6owR2D0kE) [J Med Internet Res 2018;20(1):e18]