The SmartPrompt2 iPhone app was designed according to a neuropsychological framework, empirical data, and participant feedback to support efficient completion of everyday tasks at home by sending personalized prompts to participants' smartphones. Feasibility, efficacy in the home environment, and usability were examined in ten participants with MCI or mild dementia and their care-partners (NCT04313582). Participants and care-partners identified two individually relevant tasks for the participant to complete for two weeks with the SmartPrompt2 app (SP condition) two weeks without it (Control condition; order counterbalanced). SmartPrompt2 alerted them to complete daily tasks at times specified by the participant/care-partner using personalized images, audio, rewards, and motivational and logging features targeting common errors. Care-partners reported significantly higher task completion and lower burden during the SP condition versus Control. There was no significant difference in participants' average frustration between conditions. Usability ratings were high at the end of the study, and all participants requested to keep the app. Larger and longer effectiveness studies are needed, but preliminary data support the feasibility, efficacy and usability of the SmartPrompt2 for improving everyday function in older adults with cognitive impairments.Trial Registration: NCT04313582.