The study aimed to evaluate the efficacy of a new nutritional intervention, focused on improving the quality of the diet in children aged 6 to 12 years. A 2-month parallel, controlled randomized trial was conducted in the Spanish child population. The children were randomized to ALINFA nutritional intervention, which consisted of a normocaloric diet that incorporates products, ready-to-eat meals and healthy recipes specifically designed for the study, or a control group, which received the usual advice on healthy eating. The change in diet quality was assessed through the Kidmed index. The secondary outcomes were anthropometry, glucose and lipid profiles, inflammation markers, dietary intake and lifestyle. The participants in the intervention group showed an increase in the mean score of the Kidmed index (p< 0.001). Alongside that, these children decreased their intake of calories (p= 0.046), and total and saturated fat (p= 0.016//p= 0.011), and increased fiber intake (p< 0.001). Likewise, the children in the ALINFA group increased the intake of white fish (p= 0.001), pulses (p= 0.004), whole grains (p< 0.001) and nuts (p< 0.001), and decreased fatty meat (p= 0.014), refined grain (p= 0.008), pastry (p< 0.001), fast food (p< 0.001) and sugar (p= 0.001) intake. Moreover, these children had a significantly decreased BMI (p< 0.001), BMI z-score (p< 0.001), waist circumference (p= 0.016) and fat mass (p= 0.011), as well as leptin (p= 0.004). Participants in the control group did not report significant changes in diet quality. In conclusion, ALINFA nutritional intervention is possibly a useful strategy to increase the diet quality in children, which is associated to improvements in the nutritional status. These results highlight the importance of developing well-designed nutritional interventions.