The Northern Territory (NT) and Far North Queensland (FNQ) have a high proportion of Aboriginal and Torres Strait Islander women birthing who experience hyperglycaemia in pregnancy. A multi-component health systems intervention to improve antenatal and postpartum care in these regions for women with hyperglycaemia in pregnancy was implemented between 2016 and 2019. We explored health professional perspectives on the impact of the intervention on healthcare. The RE-AIM framework (Reach, Effectiveness, Adoption, Implementation, Maintenance) underpinned this mixed-methods evaluation. Clinicians were surveyed before ( = 183) and following ( = 137) implementation. The constructs explored included usual practice and satisfaction with care pathways and communication between services. Clinicians, policymakers and the implementation team were interviewed ( = 36), exploring the impact of the health systems intervention on practice and systems of care. Survey and interview participants reported improvements in clinical practice and systems of care. Self-reported glucose screening practices improved, including the use of recommended tests (72.0% using recommended first-trimester screening test at baseline, 94.8% post-intervention, < 0.001) and the timing of postpartum diabetes screening (28.3% screening at appropriate interval after gestational diabetes at baseline, 66.7% post-intervention, < 0.001). Health professionals reported multiple improvements to care for women with hyperglycaemia in pregnancy following the health systems intervention.