The dissociative subtype of post-traumatic stress disorder (PTSD) is a distinct PTSD phenotype characterized by trauma-related dissociation, alongside unique patterns of small and large-scale functional connectivity. However, disparate findings across these various scales of investigation have highlighted the need for a cohesive understanding of dissociative neurobiology. We took a step towards this goal by conducting the largest region of interest (ROI)-to-ROI analysis performed on a PTSD population to date. While modest functional connectivity differences were found between participants with PTSD and controls in the temporal regions and the right frontoparietal network, participants with the dissociative subtype demonstrated a markedly different pattern of widespread functional hyperconnectivity among subcortical regions, sensorimotor-related networks, and other intrinsic connectivity networks, when compared to controls. Furthermore, joint brain-behavior factor analysis identified two dissociative and one PTSD symptom-linked factor. These results advance our understanding of dissociative neurobiology, characterizing it as a divergence from normative small-world organization.