Background: Delayed reporting of decreased fetal movements (DFM) could represent a missed opportunity to prevent stillbirth. Mobile phone applications (apps) have the potential to improve maternal awareness and reporting of DFM and contribute to stillbirth prevention. Aims: To evaluate the effectiveness of the My Baby's Movements (MBM) app on late-gestation stillbirth rates. Materials and Methods: The MBM trial evaluated a multifaceted fetal movements awareness package across 26 maternity services in Australia and New Zealand between 2016 and 2019. In this secondary analysis, generalised linear mixed models were used to compare rates of late-gestation stillbirth, obstetric interventions, and neonatal outcomes between app users and non-app users including calendar time, cluster, primiparity and other potential confounders as fixed effects, and hospital as a random effect. Results: Of 140 052 women included, app users comprised 9.8% (n = 13 780). The stillbirth rate was not significantly lower among app users (1.67/1000 vs 2.29/1000) (adjusted odds ratio (aOR) 0.79; 95% CI 0.51–1.23). App users were less likely to have a preterm birth (aOR 0.81; 0.75–0.88) or a composite adverse neonatal outcome (aOR 0.87; 0.81–0.93); however, they had higher rates of induction of labour (IOL) (aOR 1.27; 1.22–1.32) and early term birth (aOR 1.08; 1.04–1.12). Conclusions: The MBM app had low uptake and its use was not associated with stillbirth rates but was associated with some neonatal benefit, and higher rates of IOL and early term birth. Use and acceptability of tools designed to promote fetal movement awareness is an important knowledge gap. The implications of increased IOL and early term births warrant consideration in future studies.