Autism Spectrum Disorder (ASD) is a neurodevelopmental condition that affects communication, social behavior and gives rise to repetitive behaviors and restricted interests. The complexity of ASD suggests the influence of multiple etiological factors, including genetic, environmental and immunological elements. Recently, the gut-brain axis has emerged as a significant field of interest, proposing an intriguing connection between the composition of the gut microbiota and the neurobehavioral manifestations of ASD. This narrative review explores the current evidence linking the gut-brain axis to neuroinflammation and microglial polarization in the context of ASD. This review highlights the importance of integrated approaches to understanding the complexity of ASD, pointing to the need for further research exploring the role of the gut-brain axis as a potential therapeutic target. We conclude that a deeper understanding of the interactions between gut microbiota, neuroinflammation and microglial activity may reveal new avenues for more effective interventions in ASD.