Background/Objectives: Pediatric cancer survivors are at greater risk of cardiometabolic complications than their peers. This study evaluates the preliminary impact of the VIE (Valorization, Implication, Education) intervention, which integrates nutrition, physical activity, and psychological support, on dietary intake and cardiometabolic health among children and adolescents during cancer treatment. Methods: This comparative study includes pediatric cancer patients recruited to either the VIE intervention group or a control group receiving standard care. Post-treatment data on dietary intake, anthropometric measures, blood pressure, and biochemical parameters were compared between groups and stratified by level of involvement in the nutritional intervention and age at diagnosis (children and adolescents). Results: In the intervention group, 45 participants were included (51.1% male, mean age at evaluation 10.2 ± 4.5 years, mean time since end of treatment of 1.3 ± 0.8 years), and the control group comprised 77 participants (44.2% male, mean age at evaluation 12.0 ± 5.6 years, mean time since end of treatment of 1.4 ± 0.8 years). The intervention group had lower total caloric intake (mean: 1759 ± 513 vs. 1997 ± 669 kcal, p = 0.042) and higher calcium intake (mean: 567 ± 240 vs. 432 ± 197 mg/1000 kcal, p = 0.001). The participants who were highly involved in the nutritional intervention had greater protein-derived energy intake than the controls (mean: 17 ± 5 vs. 15 ± 4%, p = 0.029). While there was a tendency for a lesser proportion of cardiometabolic risk factors in the adolescents from the intervention group, the differences did not reach statistical significance. Conclusions: The VIE intervention improved some specific dietary intakes in the medium term after treatment completion but did not significantly impact cardiometabolic health outcomes. Additional strategies are needed to improve the diet of pediatric cancer patients, and further research is warranted to assess the long-term impact of such interventions.