The onset of schizophrenia occurs during a period critical for development of social relationships and functional independence. As such, interventions that target the early course of illness have the potential to stave off functional decline and restore functioning to pre-illness levels. In this entirely remote study, people with recent-onset schizophrenia spectrum disorders (SSDs) participated in a 12-week randomized controlled trial to determine the efficacy of PRIME (personalized real-time intervention for motivational enhancement), a mobile-based digital health intervention designed to improve motivation and quality of life. Participants were randomized into the PRIME (n = 22) or treatment-as-usual/waitlist (TAU/WL) condition (n = 21) and completed assessments at baseline, post-trial (12 wk), and for people in the PRIME condition, 3 months after the end of the trial. After 12-weeks, WL participants received PRIME, resulting in a total sample of 38 participants completing PRIME. In PRIME, participants worked towards self-identified goals with the support of a virtual community of age-matched peers with schizophrenia-spectrum disorders as well as motivation coaches. Compared to the WL condition, people in the PRIME condition had significantly greater improvements in self-reported depression, defeatist beliefs, self-efficacy, and a trend towards motivation/pleasure negative symptoms post-trial, and these improvements were maintained 3 months after the end of trial. We also found that people in the PRIME condition had significantly greater improvements in components of social motivation post-trial (anticipated pleasure and effort expenditure). Our results suggest that PRIME has the potential to be an effective mobile-based intervention for improving aspects of mood and motivation in young people with SSDs.