The widespread adoption of mobile phones and increasing mobile connectivity globally create opportunities to access remote and disadvantaged populations. Mobile health interventions in low- and middle-income countries have substantial reach and potential to promote the socio-emotional and cognitive development of children. This study presents co-design workshop findings relating to the user experience of a mobile application – Thrive by Five – which intends to promote healthy early childhood development globally, particularly in low- and middle-income countries. Here, findings from workshops conducted in 11 countries in Asia, Africa, and Oceania are presented. Key feedback on the mobile application user experience indicated several necessary changes, such as simplifying and localising the language, incorporating short videos or animations, adding more bright colours and illustrations, and making numerous improvements and additions to the app features and functionality. The findings contribute to advancing mobile health, context-sensitive technologies, user experience design, and low-resource setting technology co-design.