BackgroundParents with babies in the neonatal intensive care unit (NICU) experience high levels of stress, anxiety, and depression. The NICU experience may also lead to impaired parenting and early childhood socio-emotional problems.Psychosocial interventions can reduce NICU parent distress. Yet many are time-intensive and costly to deliver. Acceptance and Commitment Therapy (ACT), an evidence-based psychological therapy, may address these needs. ACT has been shown to be effective in reducing distress of parents of children with chronic illnesses, particularly when combined with parent education.Therefore, the primary aim of this study is to determine if a digital intervention that uses a brief form of ACT plus parent education will reduce the stress of primary caregivers with preterm babies in the NICU more than a digital education-only intervention or standard care control group. MethodsIn a randomised controlled cluster trial design, participants will be randomly assigned to one of three groups: ACT plus education; education-only; or standard care control. The primary outcome will be parental/caregiver stress levels, measured on the Parental Stress Scale: Neonatal Intensive Care Unit. Secondary outcomes include overall stress, anxiety, and depression. Outcome measures will be evaluated at baseline, two weeks after enrolment, discharge to home, and 3-months post-discharge. ConclusionThis study will explore the efficacy of a digital ACT plus education intervention on parental stress levels. While position papers have advocated for the use of ACT with NICU parents, this study will be the first to test ACT as a stand-alone intervention with this population. Trial registrationThis trial was prospectively registered with the Australian New Zealand Clinical Trials Registry on 14 June 2023 (ACTRN12623000641695p).