Very preterm (VPT) infants are at risk for altered socio-emotional stress regulation, even in the absence of perinatal complications. Moreover, becoming a mother of a VPT infant is a traumatic event, which might affect the establishment of a bonding relationship toward the infant during the postnatal period. The main aim of the present study was to assess the association between maternal postnatal bonding and socio-emotional stress response in 3-month-old VPT infants, compared to full-term (FT) controls. Thirty-three VPT and 28 FT infant-mother dyads underwent the maternal Face-to-Face Still-Face (FFSF) procedure to assess socio-emotional stress regulation. Maternal postnatal bonding was measured through the Maternal Post-Natal Attachment Scale (MPAS), which includes three scales: Quality of attachment, Absence of hostility, and Pleasure in interaction. The VPT infants exhibited less self-directed and other-directed regulatory behaviors during the Still-Face episode. Mothers of VPT infants reported lower Quality of attachment compared to FT counterparts. Importantly, higher levels of Quality of attachment were associated with more other-directed behaviors during the Still-Face episode in FT dyads, whereas this was not observed in VPT dyads. In conclusion, VPT infants might be exposed to a double-risk condition for socio-emotional development, encompassing both difficulties in stress response and the exposure to a less-than-optimal maternal bonding.