The 11 revision of the International Classification of Diseases (ICD-11) introduced Complex Posttraumatic Stress Disorder (CPTSD) as a sibling disorder to PTSD. Dissociative symptoms have been implicated in the severity of ICD-11 CPTSD; however, no reviews have investigated how dissociation has been measured in studies investigating CPTSD, nor the relationship between CPTSD and dissociation. This systematic review aimed to identify measures used to assess dissociative symptoms in studies that have assessed CPTSD according to ICD-11 criteria and to synthesize the relationship between these constructs. PsycINFO, PubMed, Scopus and Web of Science were searched on March 31, 2021. Seventeen articles met inclusion criteria. CPTSD was most frequently measured by a version of the International Trauma Questionnaire. Twelve measures were used to assess for dissociative symptoms, the most common being the Dissociative Symptoms Scale and the Dissociative Experiences Scale. The relationship between CPTSD and dissociative symptoms was moderate-to-strong, but inconsistently reported. Further research is needed to determine the most appropriate measure(s) of dissociation in CPTSD.