OBJECTIVE To examine the effectiveness of different communication strategies for mitigating language barriers on patient-, provider- and context-related outcomes. METHODS A systematic search was conducted in nine databases for quantitative studies from 2013 comparing different strategies. The studies' quality was assessed with the Evidence Project Risk of Bias tool and the certainty of evidence with the GRADE approach. RESULTS Twenty-six articles were included, all about healthcare settings. Generally, having a shared language (e.g., a provider in the patient's native language) followed by using professional interpreters yielded the most positive outcomes, and in-person or video interpreters more than telephone interpreters. Compared to professional interpreters, the translation quality of informal interpreters was only similar when assessing patient outcomes after surgery, and the quality of digital translation tools was only sufficient with simple messages or when messages were pre-translated. CONCLUSIONS Having a provider in patients' native language and having professional interpreters outperform other strategies for mitigating language barriers in healthcare. However, other strategies may suffice in specific situations. Future research should explore the effectiveness of (combining) strategies, especially in social care. CONCLUSIONS This review can inform policy and help develop guidelines on mitigating language barriers to support providers in their daily practice.