Background <p>The <i>Tracking Cube</i> is a co-designed, digitally-embedded solution that supports neurodevelopmental care for children and adolescents in primary healthcare. It aims to enable culturally-responsive, community-based care by providing clinical decision-support tools for ongoing screening, assessment, triage, and support. Current practice in Australia lacks consistent, system-wide management of developmental risk, particularly in services for First Nations children, leading to inequities in identification, support and referral. Pilot findings have indicated that the <i>Tracking Cube</i> can accelerate adoption of best practice, improve triage accuracy, provide timely, culturally-responsive support within primary care, and reduce unnecessary referrals to specialists. This trial will assess its effectiveness and implementation across seven diverse primary healthcare sites serving First Nations children.</p> Methods <p>This type 1 hybrid effectiveness-implementation trial combines a stepped-wedge cluster randomised trial to assess effectiveness, with a mixed-methods implementation evaluation guided by the EPIS framework. Seven sites (defined as geographic regions that encompass one or more service delivery locations) not currently using standardised neurodevelopmental screening and triage for individuals under 18 years will be randomised to implement the <i>Tracking Cube.</i> Sites will commence in 2-month intervals; data will be collected over a 6-month baseline, 24-month intervention, and 6-month sustainability phase. Effectiveness outcomes (increased identification of neurodevelopmental concerns and disorders, improved follow-up in primary healthcare, and more appropriate specialist referrals) will be evaluated via longitudinal chart audits. Implementation strategies will be documented, and outcomes (barriers, enablers, accessibility, acceptability, appropriateness, feasibility, and readiness) will be evaluated through a place-based learning database, journey tracking database, and healthcare provider and family surveys and interviews.</p> Discussion <p>This trial addresses healthcare system gaps by embedding neurodevelopmental care into routine practice through a culturally grounded, co-designed model. Sharing knowledge across community, industry, and academia resulted in a strengths-based, holistic approach that supports children whose developmental needs are often overlooked due to systemic failures. By conducting a rigorous stepped-wedge cluster randomised trial and documenting implementation strategies, outcomes from this trial could showcase how the uptake of a complex intervention can be accelerated across diverse contexts. If effective, the <i>Tracking Cube</i> could inform an equity-focused, scalable solution for neurodevelopmental support within primary healthcare that maintains site-specific relevance.</p> Trial registration <p>This trial is registered: ACTRN 12624001116516; Date of registration 17-09-24, <a href="https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12624001116516">https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12624001116516</a></p>