Autism spectrum disorders (ASDs) are diagnosed exclusively on behavioral criteria, however, there is a broad consensus that autism is a disorder of brain development. Although not a diagnostic feature, substantial evidence demonstrates that emotion dysregulation (ED) is associated with autism. However, little is known about the brain patterns accompanying the emergence of early ED in children with ASDs in the first years of life. The brain salience network (SN) is critically implicated in detecting and orienting to relevant internal and external stimuli, and is a key player in affective and empathic processing underlying emotion regulation. The present study aims (a) to advance our understanding of ED emergence in ASDs and its role in core autism symptoms, and (b) to identify SN connectivity patterns supporting emotional processing in toddlers with first symptoms of ASDs. Toddlers and preschoolers with an ASD diagnosis and typically developing (TD) children were drawn from an ongoing study of early brain markers of ASDs. The Full Cohort included 49 children with ASDs and 37 age-matched TD children with complete behavioral data; the Imaging Cohort included 25 children with ASDs and 23 TD children with complete MRI (both cohorts ages 1.5 to 4 years). Children completed 2 visits: a developmental assessment and an MRI scan session during natural nocturnal sleep. Results revealed that children in the ASD group displayed more ED behaviors compared to TD children, and higher ED was linked to deficits in socialization skills. Whole-brain seed-based and ROI-ROI functional connectivity analyses were performed for the SN, with seed ROIs in the right and left anterior insula (rAI, lAI) and dorsal anterior cingulate cortex. Direct between-group comparisons revealed greater connectivity within the SN, especially between the rAI and lAI, and weaker connectivity between the SN and frontal regions in children with ASDs. There were no significant associations between emotional reactivity indices and SN connectivity patterns. Findings provide insight into early onset of ED in toddlers and preschoolers with ASDs, and have substantial implications for developing more targeted interventions. Moreover, atypical SN connectivity patterns point to evidence of network dysfunction at the time when autism symptomology first emerges.