Health literacy is a key determinant of health in refugee and migrant populations living in in high-income countries (HICs). We conducted a systematic review of randomized-controlled trials (RCTs) to characterize the scope, methodology, and outcomes of research on interventions aimed at improving health literacy among these vulnerable populations. We searched EMBASE, MEDLINE, PsycINFO, CINAHL, and Web of Science databases to identify RCTs of health literacy intervenions in our target population published between 1997 and 2018. The search yielded 23 RCTs (n = 5625 participants). Study demographics, health literacy topics, interventions, and outcome measures were heterogeneous but demonstrated overall positive results. Only two studies used a common health literacy measure. Few RCTs have been conducted to investigate interventions for improving the health literacy of refugees and migrants in HICs. The heterogeniety of health literacy outcome measures used impeded a robust comparison of intervention efficacy.