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Objective To investigate whether gestational diabetes mellitus (GDM) was associated with survival without bronchopulmonary dysplasia (BPD) in very preterm infants (VPIs).Design Retrospective multicentre cohort study.Setting A total of 79 neonatal intensive care units across China, January 2019 to December 2021.Participants A total of 23 752 VPIs (<32 weeks’ gestation) or very low birth weight infants (<1500 g), comprising 4452 GDM-exposed and 19 300 unexposed infants.Main outcome measures The primary outcomes are survival without BPD at 36 weeks’ postmenstrual age (PMA) and its components.Results Infants exposed to GDM were associated with a higher rate of survival without BPD (aOR 1.12, 95% CI 1.04 to 1.21) at 36 weeks PMA and lower mortality (aOR 0.75, 95% CI 0.64 to 0.84) before 36 weeks PMA than unexposed infants. However, no significant association was observed between GDM and BPD at 36 weeks PMA (aOR 0.94, 95% CI 0.87 to 1.02), respiratory distress syndrome, need for advanced resuscitation or mechanical ventilation. After propensity score matching, GDM-exposed VPIs maintained higher survival without BPD (aOR 1.13, 95% CI 1.02 to 1.26) and lower mortality (aOR 0.81, 95% CI 0.68 to 0.97). These associations were strongest in infants born before 28 weeks (aOR 1.32, 95% CI 1.11 to 1.57) and those small for gestational age (aOR 1.41, 95% CI 1.11 to 1.80).Conclusions GDM was not associated with worsened BPD in VPIs. The positive association with survival and survival without BPD warrants could reflect a selection bias.