Background: Depression is a major public health concern. E-health interventions for preventing and reducing depressive complaints have proven to be effective, and have the potential to make (mental) health care more accessible and efficient. However, the reach of these interventions needs to be improved, especially among people with a lower socioeconomic status (SES). Stimulating and supporting implementation of e-health in primary care, and offering guidance from general practice nurses (GP nurses) may be important strategies to achieve this. Methods/design: The online 'Complaint Directed Mini-Interventions' (CDMIs) for stress, sleep and worry complaints, which were found to be (cost-)effective in a self-guided format, will be implemented in the primary care setting using a blended care format (i.e. combining e-health with face-to-face sessions) with minimal guidance provided by the GP nurse. The main aim is to evaluate whether a SES-sensitive implementation strategy improves the participation rate (i.e. reach) of lower-SES patients in the blended online CDMIs as compared to a regular implementation strategy in a cluster randomised controlled trial. Randomisation will occur at the level of the GP nurse, and 228 patients will be included in the study. The primary outcome is the participation rate (completing at least one face-to-face session and two online exercises) of the lower-SES target group. It is hypothesised that this percentage will be higher in the SES-sensitive group as compared to the regular group. Secondary objectives are to evaluate the implementation process, to monitor and evaluate psychological complaints (depression, sleep, stress, worry and anxiety) and well-being over time. Patient assessments will take place at baseline, 3 and 12 months post baseline. Discussion: This study should contribute to our knowledge of reaching the lower-SES groups with a brief and complaint-specific blended approach for depressive complaints in primary care. It should also further our knowledge on successful strategies to implement depression prevention in primary care. Trial registration: Netherlands Trial Register, ID: NL6595. Registered on 12 November 2017.