Poor oral health is common in nursing home residents, and health care professionals report numerous barriers when it comes to the provision of oral care for care-dependent older adults, such as a lack of oral health knowledge and skills, care-resistant behaviors in residents, lack of adequate oral care routines, insufficient systems for documentation of issues related to oral health, a high workload, and unclear responsibilities. An intervention, SmartJournal, has been developed to assist health personnel in preserving older patients' oral health. SmartJournal is a digital tool with three components: (1) documentation of oral hygiene routines; (2) monthly oral health assessment; and (3) education on geriatric oral care. An updated framework for research on complex interventions has been used to guide the various phases in the development of this intervention. This study focuses on the evaluation phase. We aim to assess (1) the effectiveness of SmartJournal use in enhancing nursing home caregivers' capability, opportunity, motivation, and routines related to oral care; and (2) whether SmartJournal use results in improved oral health for nursing home residents. We will use a cluster randomized controlled trial to assess impacts of SmartJournal use as specified under study objectives. Nursing homes located in Rogaland, Norway, will be recruited and randomly assigned to an intervention and a control group. The intervention group will be provided with tablets containing SmartJournal and support from research staff, while the control group will continue with existing oral care routines. Both groups will receive oral hygiene packages. The intervention will last for 12 weeks. Measurements will be performed in both groups at baseline, 3 months, and 9 months and include (1) a survey assessing caregivers' capability, opportunity, motivation, and routines related to oral care; and (2) assessment of oral health status in residents using mucosal-plaque score as a primary outcome measure. Analyses will include descriptive statistics and statistical techniques to look for changes and differences in the study variables within and between the intervention and control groups throughout the study period. Associations between study variables will also be investigated. Recruitment of nursing homes for the intervention and control groups was completed in February 2023. Recruitment of individual participants (ie, nursing home residents and caregivers) is ongoing, and baseline measurements are being performed consecutively. Results are expected to be ready for analyses in fall 2024. We aim to assess the effects of SmartJournal use on oral care and oral health in nursing homes. Results from this work may inform further development and implementation of SmartJournal and similar digital tools aiming to enhance health care services offered to care-dependent people. Finally, SmartJournal may have potential as a learning tool in educational programs for nurses and other health care professionals. ClinicalTrials.gov NCT05724043; https://clinicaltrials.gov/study/NCT05724043. DERR1-10.2196/46926.