BackgroundInformal caregivers of people with dementia are crucial in dementia care. However, they are insufficiently supported and report caregiver burdens, which urges the need for cost-effective interventions aimed at supporting caregivers. This paper presents the design of a study evaluating the effectiveness, cost-effectiveness, and cost-utility of a blended self-management program for early-stage dementia caregivers.Methods/designA pragmatic, cluster randomized controlled trial with a shared control group will be conducted. Participants will be informal caregivers of people with early-stage dementia and will be recruited by local care professionals. Randomization will be carried out at the level of the care professional level in a ratio of 35% to 65% (control arm vs. intervention arm). Participants in the control arm will receive care as usual and the intervention arm will receive the blended care self-management program “Partner in Balance” within a usual care setting in the Netherlands. Data will be collected at baseline and at 3-, 6-, 12-, and 24-month follow-ups. The primary outcome for effectiveness (part 1) is care management self-efficacy. For the health-economic evaluation (part 2) total care costs and the quality of life for individuals with dementia (cost-effectiveness) and quality-adjusted life years (cost-utility) will be the base case analysis. Secondary outcomes (parts 1 and 2) will include depression, anxiety, perceived informal caregiving stress, service-use self-efficacy, quality of life, caregivers’ gain, and perseverance time. A process evaluation (part 3) will investigate the internal and external validity of the intervention.DiscussionIn this trial, we plan to evaluate the effectiveness, cost-effectiveness, and cost-utility of “Partner in Balance” among informal caregivers of people with dementia. We expect to find a significant increase in care management self-efficacy, and the program to be cost-effective, and provide valuable insights to stakeholders of “Partner in Balance.”Trial registrationClinicalTrials.gov, NCT05450146. Registered on 4 November 2022.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13063-023-07423-9.