BACKGROUND: Given that anxiety is associated with functional disability, we investigated whether an intervention designed to reduce prenatal anxiety could improve functional disability in the postpartum period. We also examined whether perceived social support in the third trimester mediated this relationship, and if the extent of the mediation differed by economic empowerment. METHODS: We included 590 pregnant Pakistani women with at least mild anxiety symptoms to a randomized controlled trial (RCT). Women in the intervention arm received six sessions of a Cognitive Behavioral Therapy-based psychosocial intervention for prenatal anxiety. Relaxation techniques (e.g., breathing exercises and meditation) and enhancement of social support were also included in the therapy. The control group received enhanced usual care. Economic empowerment was dichotomized into empowered and non-empowered. We used the Multidimensional Scale of Perceived Social Support (MSPSS) to assess social support, where higher scores indicated greater social support. The WHO Disability Assessment Schedule (WHODAS 2.0) was employed to evaluate functional disability which was neither a primary nor a secondary outcome of the RCT. As an ad hoc analysis of the RCT, regression-based path analysis modeling was employed to examine the main, mediating, and moderating effects. Mediation was estimated with the product of coefficients method. RESULTS: The intervention reduced the postpartum functional disability by 4.7 points (adjusted B = -4.71, bootstrapped 95 % confidence interval (CI): -5.93, -3.49), and social support in the late pregnancy mediated this relationship (B CONCLUSION: While social support can mediate the relationship between psychosocial intervention and functional disability in anxious pregnant women, promotion of social support during late pregnancy may be particularly useful in non-empowered women, for reducing functional disability in the postpartum period.