<p>Autism spectrum disorder (ASD) is a multifactorial, neuro-psychiatric, and neurodevelopmental illness possessing impaired social, behavioral, and communicative presentations. Research suggested the important role of the gut-brain axis in ASD, especially related to gut dysbiosis and mitochondrial dysfunction. This review comprehensively summarizes the existing evidence of the association between gut microbiota, microbial metabolites, and mitochondrial dysfunction in ASD, comprising of clinical, experimental, and epidemiological data over the last decade. The focus was on the research that clarifies the gut-mitochondria crosstalk and role in ASD pathophysiology. ASD patients demonstrate a substantial shift in the variety of gut microbiota, such as a decrease in the number of beneficial microbes and the growth of pathogenic taxa. These changes affect the biosynthesis of major neuroactive metabolites executing immune modulation and neurotransmission. The review detects the microbial metabolites that regulate mitochondrial activity through mechanisms like vagus nerve, intestinal hormones, and immune signaling. The different mitochondrial signaling pathways were inhibited including AMPK, mTOR, and NF-κB. Preventive interventions that concentrate on modulation of the microbiome and mitochondria may present a prospective line of therapy. Nevertheless, uncovered gaps should be mentioned in future research, multi-omics studies, longitudinal studies, and the protocol to understand the components of gut-brain axis in ASD to develop personalized therapy.</p>