Background: Multiple sclerosis (MS) is a chronic immune-mediated central nervous system disorder that affects females twice as often as males. MS patients show increased susceptibility to obesity and related cardiometabolic disorders, while diet may influence disease course. In the present randomized controlled study, we aimed to increase Mediterranean Diet (MedDiet) adherence in MS women and improve their nutritional status. Methods: Adult women with relapsing-remitting MS (n = 40) were randomly allocated to intervention (n = 20) or control group (n = 20). Individual dietary plans based on MedDiet together with nutritional consultation were provided to the intervention group. Controls received general lifestyle advice according to “National Dietary Guidelines”. Medical history, anthropometry, dietary records, and blood withdrawal were performed at baseline and at 3 months. Results: Compared to controls, the intervention group demonstrated greater MedDiet adherence (p < 0.001), which was negatively associated with cholesterol intake levels (p < 0.05). At 3 months, women following MedDiet had ameliorated body weight and body composition compared to baseline (p < 0.001). Serum 1,25(OH)2D was significantly higher in both study groups at 3 months (p < 0.001), but in the intervention group, the mean increment was twofold compared to controls (p < 0.001). Conclusion: Personalized nutritional intervention in MS patients may improve MedDiet adherence and nutritional status towards cardioprotective health outcomes.