Introduction Very-low birthweight (VLBW, <1500 g) infants comprise about 1%-1.4% of all births in high-income countries. Every year, about 3000 VLBW babies in Australia and New Zealand receive intensive care. Many die or else survive with severe brain injury, retinopathy, late-onset sepsis or necrotising enterocolitis (NEC), each of which carries substantial risk of disability. Methods and analysis This trial tests whether adding bovine lactoferrin (bLF) to feeds in VLBW infants improves (1) survival to hospital discharge free from brain injury, late-onset sepsis, NEC and treated retinopathy of prematurity (primary composite end point); (2) each component of the primary composite end point and (3) time to reach full enteral feeds, number of blood transfusions, chronic lung disease and length of hospital stay. It includes a cost-effectiveness analysis of bLF in improving survival free from major morbidity, and evaluates the effect of bLF on survival and developmental outcomes at 24 to 36 months corrected gestational age. This is a multicentre, two-arm, randomised trial comparing the treatment group receiving bLF added to breast milk or formula milk daily (up to 250 mg/kg/day bLF) versus the control group receiving no bLF supplementation. The intervention is administered until 34 completed weeks corrected gestation or for 2 weeks, whichever is longer, or until discharge home, if earlier. The target sample size of 1500 participants yields 85% power, at the two-sided 5% level significance, to detect a difference in proportions meeting the primary outcome assuming the true probability is 74% in controls and 80.5% in the bLF group. Ethics and dissemination This protocol was approved by Northern Sydney Local Human Research Ethics Committee in January 2017 (Version 2.0, Reference 1003-118M) and other relevant ethics committees. The findings of the trial will be disseminated through peer-reviewed journals and conference presentations.