This narrative synthesis aims to examine the dietary intake, diet quality, and dietary preferences of pediatric cancer patients during cancer treatment. Thirteen studies were eligible for review. Studies mostly investigated nutrient intake, with 7 reporting on children’s food intake. There was consensus among studies, which reported suboptimal fruit and vegetable intake and a preference for savory, carbohydrate-based foods. Results suggest that pediatric cancer patients consume a limited variety of foods, with a high intake of noncore foods. Future research should aim to examine dietary food data against dietary guidelines to assess adequacy and variety within core food groups.