Background: Childhood overweight/obesity constitutes a serious issue, as may cause several health problems. The main characteristics of the Mediterranean Diet have been acknowledged as the most appropriate shield mainly for obesity. Methods: The study was performed on 1728 primary students, during school years 2014-2016, in Greece. Children and their parents completed questionnaires which included dietary and lifestyle habits. The KIDMED score (range-4 to 12) was used to assess the level of childhood adherence to the Mediterranean diet and the MedDietScore (range 0 to 55) was used to assess parental adherence. For the purposes of this analysis, the examined sample was n = 875 of students (522 girls)-parents pairs whose level of adherence to the Mediterranean diet was able to be evaluated. Results: The prevalence of overweight and obesity in the Greek sample was 26.0%, according to International Obesity Task Force (IOTF) cutoff criteria for children. KIDMED Score was significantly lower in children with overweight/obesity compared with children with normal weight (4.65 ± 2.14 vs. 5.16 ± 2.05, p = 0.002). The multiadjusted analysis revealed that children close to the Mediterranean diet were less likely to be overweight/obese (p < 0.001), either parents are away from or close to the Mediterranean diet. Conclusions: This study revealed that children's adherence to the Mediterranean diet was inversely associated with weight status either parents are away from or close to this dietary pattern. Future interventions against childhood obesity have to take into consideration the crucial importance of familial aggregation of healthy food choices and interfamily influences in the home environment on children's weight status.