Purpose: The purpose of this systematic review was to identify, appraise, and critically synthesize the latest available evidence on the effects of augmentative and alternative communication (AAC)-based interventions on communication skills in children aged between 6 and 10 years with mixed diagnoses. Method: MEDLINE (OVID), PsycINFO (EBSCO), ERIC (ProQuest), SCIELO (WOS), Teacher Reference Center (EBSCO), and Education Database (ProQuest) were searched. The studies were independently selected by two reviewers for the purposes of the review. The methodological quality of the included studies was assessed, and characteristics and results of the studies were extracted. Results: This review included 14 studies from a total of 1,204 found through an electronic search. The AAC interventions studied were effective at improving various outcomes in children with mixed diagnoses. Interventions that focused on narrative skills were the most common type. When considering the quality of the studies, the independence of assessors, data analysis, replication, and generalization of interventions were the weaker areas. Conclusions: Interventions analyzed in this review improve communication skills, including phonological awareness, vocabulary, requesting, and developing narrative skills in children aged between 6 and 10 years with mixed diagnoses. The results of one study also indicate that the acquisition of skills using an AAC method is superior when the child prefers the method.