Background Northland, New Zealand has a generally socioeconomically deprived population with a high proportion of indigenous Māori. Māori youth suffer a high rate of mental ill-health, substance misuse, and other risky behaviours. While evidence demonstrates that early detection and management of these issues leads to long-term positive health outcomes, implementation of systematic screening and intervention is challenging. This study aimed to implement YouthCHAT, a self-administered digital tool screening young people for mental health concerns and risky health behaviours, into youth services in Northland using an iterative process of implementation, evaluation, and modification, and to create a framework for national-level rollout and implementation.Methods Normalisation Process Theory and a Māori research approach informed the implementation and its evaluation. Data sources included end-user focus groups, staff surveys, field notes, and informal communications with key stakeholders. Number of YouthCHAT screens completed measured intervention uptake.Results: Ongoing staff and youth feedback led to changes in YouthCHAT which increased acceptability. Facilitating two-way communication between providers and management, providing accessible training, and improved e-health record integration assisted uptake. Contextual factors, such as establishing a bicultural co-design approach and programming remote functionality during COVID-19 lockdown, were important factors in YouthCHAT’s ultimate acceptability and implementation. Other impediments such as staff redeployed during meningococcal and measles epidemics merely required patience. An implementation framework for YouthCHAT was developed which addresses tool acceptance and uptake, requiring ongoing effective communication and coordination, and iterative evaluation.Conclusions Failure to launch may be due to the interplay between the intervention, its users, contextual factors, and wider organisational aspects. Interventions may need to be tailored to a specific context to meet the needs of users, and address organisational and system barriers. Ultimately there will only be uptake where providers see this as worthwhile. Perception that its effective use will reduce their workload serves as a valuable incentive. The participatory research and bicultural Māori approaches employed in this project eventually led to YouthCHAT’s successful implementation in Northland. Full ownership of the Northland YouthCHAT version was transferred to local stakeholders on project completion. An iterative and evaluative strategy is recommended for future implementation. While derived for a specific population, the principles are generic, and our framework should be generalisable to other settings.Trial registration Australian and New Zealand Clinical Trials Registry ACTRN12618000299202p, 16-02-2018; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374532