Early efforts for prevention of childhood overweight and obesity are needed. In order to adapt an app promoting healthy diet and physical activity behaviors in children (MINISTOP 1.0) for multi-ethnic communities, we explored: (1) needs and concerns among Somali-, Arabic-, and Swedish-speaking parents in terms of supporting healthy diet and activity behaviors in their children; (2) nurses’ perceptions of parental needs and concerns in relation to diet and physical activity behaviors; and (3) how the features and content of the MINISTOP 1.0 app could be refined to better support health behaviors in children, among both parents and nurses. Focus groups with Somali-, Arabic-, and Swedish-speaking parents (n = 15), and individual interviews with nurses (n = 15) were conducted. Parents expressed several challenges in supporting children’s health behaviors, the need for a tailored app, and alternative ways of accessing the content (audio/video). Nurses emphasized the need of supporting parents early, and the value of a shared platform in different languages, to facilitate communication. This study contributes valuable insights about parental needs and relevant adaptations to a parental support app, such as addition of audio/video files for increased accessibility. This adapted app version—MINISTOP 2.0, can be useful for childhood obesity prevention in multi-ethnic communities.