Autism Spectrum Disorder (ASD) is a multifaceted developmental condition marked by challenges in social interaction, limited interests, and repetitive patterns of behavior. The causes of ASD remain poorly understood. People with ASD may exhibit a range of behavioral symptoms, including hyperactivity, distractibility, impulsiveness, aggression, self-harming behaviors, temper tantrums, and sleep problems. Additionally, feeding difficulties such as food selectivity, along with gastrointestinal (GI) symptoms, are commonly reported. The prevalence of GI issues, including diarrhea, constipation, chronic bowel conditions, and general GI dysfunction, varies significantly among children with ASD. The association between GI symptoms and ASD suggests that the gut microbiota may play a significant role in the disorder. Emerging evidence highlights a potential link between the gut-brain axis, gut microbiota, and ASD, driving growing interest in probiotics as a therapeutic intervention. Live microorganisms, known as probiotics, offer various health advantages when consumed in sufficient quantities, may influence intestinal epithelial cells, facilitate gut-brain communication, and modulate immune responses, potentially offering improvements for individuals with ASD. This review examines the current literature on the efficacy of probiotic treatment in ASD, focusing on clinical outcomes and mechanisms of action in this population. While studies show promising results, including improvements in GI symptoms, ASD core symptoms, behavior, and social functioning, the variability in patient characteristics, study designs, small sample sizes, and the types and durations of probiotics administered underscores the need for further research. Large-scale randomized controlled trials are essential to develop standardized protocols and to understand better the long-term effects, as well as the optimal strains and dosages of probiotics for individuals with ASD.