This study aims to examine the prevalence of multiple types of child victimization and the effects of multiple types of victimization on children’s mental health and behavior in Taiwan. The study also examines the child-protection rate and its correlates among children experiencing various types of victimization. This study collected data with a self-report questionnaire from a national proportionately stratified sample of 6,233 fourth-grade students covering every city and county in Taiwan in 2014. After calculating the 1-year prevalence of child victimization, the study found that bullying was the most prevalent (71%), followed by physical neglect (66%), psychological violence (43%), inter-parental violence (28%), community violence (22%), physical abuse (21%), and sexual violence (9%). As the number of victimization types increased, children were more likely to report greater posttraumatic symptoms, psychiatric symptoms, suicide ideation, self-harm thoughts, and violent behaviors. Gender, neonatal status, parental marital status, and other family risks were significantly associated with elevated incidences of the victimization types. Only 20.6% of the children who had experienced all seven types of victimization had received child protective services. A child was more likely to receive child protective services if he or she had experienced sexual violence, community violence, inter-parental violence exposure, higher family risks, higher suicidal ideation, or living in a single-parent or separated family. In conclusion, this study demonstrates the cumulative effects and the harmful effects that children’s experience of multiple types of victimization can have on the children’s mental health and behavior. The present findings also raise alarms regarding the severity of under-serving in child-victimization cases. These results underscore the importance of assessing, identifying, and helping children with multiple victimization experiences.