Background: Young people, aged 15-25 years, are at a critical stage of life when they need to navigate vocational pathways and achieve work and study outcomes. Those with mental health problems are particularly at risk of disengagement with work and study and need effective support. The headspace Work and Study (hWS) service is an innovative online platform implemented in Australia to support young people aged 15-25 years with mental health problems to achieve work and study goals. Objective: This study aims to determine whether the hWS service has been implemented as planned, provides appropriate support for young people, and achieves its main goals. Methods: Data were collected via 2 methodologies: (1) the hWS Minimum Data Set, which includes data on all clients in the service (n=1139), services delivered, and service impact; and (2) a survey of hWS clients who volunteered to participate in an evaluation of the hWS service (n=137). Results: The service was accessed by its defined target group, young people aged 15-25 years with mental health and work and study difficulties. Young people found the online platform to be acceptable, and the assistance provided and clinical integration useful; many young people achieved positive work and study outcomes, particularly those who engaged more times with the service. More assistance was sought for work than study goals, suggesting that the transition to work may be particularly challenging for young people. One-third (298/881, 33.8%) of the sample for the service impact analyses achieved at least 1 primary work or study outcome, and this increased to 44.5% (225/506) for those who engaged with 5 or more sessions, demonstrating that greater engagement with the service produced better outcomes. Conclusions: Critical work and study support can be effectively delivered via an online modality to young people with common mental health problems. Digital services are scaleable to reach many young people and are of particular value for those with difficulty accessing in-person services.