Background: Given the lack of healthcare access in the Republic of the Marshall Island (RMI) and the potential for complications related to type 2 diabetes mellitus (T2DM) and hypertension, it is crucial to examine these conditions among Marshallese in the RMI. Objectives: This study aims to identify the proportion of Marshallese adults in the RMI with undiagnosed T2DM and hypertension. Design: Using a community-based participatory research approach, screening events were conducted at 20 churches in Majuro Atoll. Methods: Participants completed a questionnaire and biometric data measures, including hemoglobin A1c and blood pressure. Results: Among participants with blood pressure data ( N = 528), 11.9% had readings indicative of hypertension, and 38.1% were undiagnosed. Among participants with hemoglobin A1c (HbA1c) data ( N = 450), 45.3% had readings indicative of T2DM, and 39.2% were undiagnosed. Conclusion: This study utilized a community-based participatory research approach that promotes equitable and ethical research. Results reaffirm the need to identify strategies for increasing healthcare access and for research to address health disparities in the RMI.