More than half the global population is estimated to be multilingual, yet research on autistic children who grow up in multilingual environments remains scant. We conducted a systematic review of peer-reviewed studies on multilingualism in autistic children and its impact on children's language and communication skills. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, our search identified 22 group comparison studies published from 2011 to 2022. The current review addressed two main questions: (a) Which language and communication skills of multilingual autistic children were assessed and how; and (b) how the skills of multilingual autistic children compared with their peers. Semantic-related skills were most frequently reported, while phonology and pragmatics were the most underreported dimensions of language. Most reviewed studies used a combination of direct and indirect language assessments. Available research provides no indication that being exposed to more than one language has adverse effects on the communication skills of autistic children. Although multilingual autistic children often have common autism characteristics, such as pragmatic difficulties affecting their communication skills, preliminary findings also indicate that they may share some advantages of multilingualism with their multilingual nonautistic peers. Studies often excluded participants with co-occurring diagnoses, which may have impacted the generalizability of the findings.