Background: Prematurity and low birthweight are more prevalent among Indigenous and Culturally and Linguistically Diverse infants. Methods: To conduct a systematic review that used the social-ecological model to identify interventions for reducing low birthweight and prematurity among Indigenous or CALD infants. Scopus, PubMed, CINAHL, and Medline electronic databases were searched. Studies included those published in English between 2010 and 2021, conducted in high-income countries, and reported quantitative results from clinical trials, randomized controlled trials, case-control studies or cohort studies targeting a reduction in preterm birth or low birthweight among Indigenous or CALD infants. Studies were categorized according to the level of the social-ecological model they addressed. Findings: Nine studies were identified that met the inclusion criteria. Six of these studies reported interventions targeting the organizational level of the social-ecological model. Three studies targeted the policy, community, and interpersonal levels, respectively. Seven studies presented statistically significant reductions in preterm birth or low birthweight among Indigenous or CALD infants. These interventions targeted the policy (n = 1), community (n = 1), interpersonal (n = 1) and organizational (n = 4) levels of the social-ecological model. Interpretation: Few interventions across high-income countries target the improvement of low birthweight and prematurity birth outcomes among Indigenous or CALD infants. No level of the social-ecological model was found to be more effective than another for improving these outcomes.