This paper aims to describe the use ADDIE model in developing a digital health tool, OSOMO Prompt app, and discuss evaluation outcomes of using this digital tool by village health volunteers (VHV) in rural areas in Thailand. The OSOMO prompt app was developed and implemented in elderly populations in eight rural areas. The Technology Acceptance Model (TAM) was used to test the acceptance of the app four month after the implementation. There were 601 VHVs voluntarily involved in the evaluation phase. The ADDIE model was successfully employed to guide the research team to develop the OSOMO Prompt app consisting of four services delivered to elderly populations by VHVs, including: 1) health assessment; 2) home visit; 3) knowledge management; and 4) emergency report. The findings from the evaluation phase reported that the OSOMO Prompt app was accepted as utility and simplicity (score 3.95+.62); and valuable digital tool (score 3.97+.68). The app received the highest score for being a useful tool assisting VHVs in achieving their work goals and improving work performance (score 4.0+.66). The OSOMO Prompt app could be modified for other healthcare services in different populations. Further investigation in long-term use and its impact on healthcare system is warranted.