Background: Global developmental delay (GDD) is a significant concern in early childhood, often indicative of underlying conditions. Despite their rarity, GDD should be considered among the metabolic abnormalities when these diseases are present. Objectives: This study aimed to identify the rates and range of MSDs in young children with GDD, investigate the outputs from these metabolic disturbances on development, and establish the efficiency of integrated metabolic screening. Methods: This prospective cohort study involves 85 children between 3 months and two years diagnosed with GDD. Other metabolic investigations included targeted metabolic panels, urine organic acid tests, and plasma acylcarnitines. Clinical data and developmental assessments were gathered as well. Results: Metabolic abnormalities were identified in 32.9% of participants, with amino acidopathies, organic acidemias, and mitochondrial disorders being the most prevalent. Results revealed that children with metabolic abnormalities achieved significantly poorer results on tests measuring their development. Pre-surgical diagnosis and evaluation indicated the potential of early treatment in enhancing child developmental functions. Conclusions: Therefore, this study emphasizes the need for metabolic screening in children diagnosed with GDD. The genesis and timely assessment of metabolic disorders can provide developmental benefits. It is advisable to operate under a screening paradigm to enhance the detection of possible abnormalities and inform relevant actions.