There is little understanding of the circumstances behind fatal pediatric opioid poisonings. Our objective was to characterize opioid fatalities according to child, family, and household factors. We used data from the National Fatality Review-Case Reporting System to describe the circumstances behind the deaths of children 0 to 17 years of age who died of an opioid poisoning (ie, prescription opioid, heroin, illicit fentanyl) between 2004 and 2020. Decedents were stratified into age groups: 0-4, 5-9, 10-14, and 15-17 years. The majority (65.3%) of the 1696 fatal opioid poisonings occurred in the child's own home. Prescription opioids contributed to 91.8% of deaths, heroin contributed to 5.4%, and illicit fentanyl to 7.7%. Co-poisonings with nonopioid substances occurred in 43.2% of deaths. Among 0- to 4-year-olds, 33.9% died of homicide and 45.0% had a primary caregiver with a history of substance use/abuse. Among 10- to 14-year-olds and 15- to 17-year-olds, respectively, 42.0% and 72.8% of decedents had a history of substance use/abuse. In each age group, at least 25.0% of children were victims of previous child maltreatment. A history of maltreatment and substance use-whether on the part of the caregiver or the child-are common factors surrounding fatal pediatric opioid poisonings, the majority of which occur in the child's own home. Families with children of all ages would benefit from interventions focused on opioid prescribing, storage, disposal, and misuse. These findings also underscore the urgency of ensuring that access to naloxone becomes universal for families with a history of maltreatment and/or substance use.