BACKGROUND: Psoriasis is an inflammatory disease primarily treated through molecular-targeted therapies. However, emerging evidence suggests that dietary interventions may also play a role in managing inflammation associated with this condition. The Mediterranean diet (MedDiet), prevalent in southern European countries, has been widely recognized for its ability to reduce cardiovascular mortality, largely due to its anti-inflammatory properties. This anti-inflammatory potential has prompted interest in exploring the MedDiet's role in immune-mediated diseases, including psoriasis. Observational studies have indicated potential benefits, such as reductions in the Psoriasis Area and Severity Index. However, there is a need for well-designed clinical trials to address the methodological limitations of these studies and to establish specific dietary recommendations for psoriasis. OBJECTIVE: This study aims to evaluate the impact of an intensive dietary intervention based on the MedDiet in patients with psoriasis. The study will assess the effects of this intervention on skin involvement, metabolic parameters, and inflammatory cytokines. In addition, the emotional well-being and quality of life of participants will be evaluated using validated questionnaires. A methodological analysis will also be conducted to enhance the design of future large-scale clinical trials. METHODS: An open-label, single-blinded (evaluator) randomized controlled trial was designed to assess the impact of a high-intensity MedDiet intervention in patients with mild-to-moderate psoriasis. A total of 38 patients will be randomly assigned into 2 groups-an intervention group receiving the MedDiet intervention and a control group receiving standard care. The intervention group will participate in dietary education sessions aimed at adopting the MedDiet over 4 months, with monthly monitoring by experienced nutritionists. Participants will receive 500 mL of extra virgin olive oil per week, along with informative materials, recipes, and weekly menus. In contrast, the control group will receive standard low-fat diet recommendations without nutritionist monitoring. All participants will undergo a baseline visit, a 2-month follow-up visit, and a final visit at 4 months. Blood tests will be conducted at the beginning and end of the study. This study protocol was approved by the Institutional Review Board of the Hospital Ramón y Cajal (Madrid) in July 2023. RESULTS: Enrollment concluded in October 2024, with data collection set to finish by February 2025. The findings will be presented at national and international conferences and published in peer-reviewed journals. CONCLUSIONS: This protocol outlines the design of a clinical trial that implements the MedDiet in patients with psoriasis to evaluate its benefits on skin involvement, systemic inflammation, and quality of life. TRIAL REGISTRATION: ClinicalTrials.gov NCT06257641; https://clinicaltrials.gov/study/NCT06257641. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/64277.