The COVID-19 public health crisis has created significant challenges for children in British Columbia. These challenges have included most children facing restrictions in their contacts with family members and friends, as well as temporary school closures. Many children are also part of families that have experienced economic hardships. Beyond the social, educational and economic costs, there will also be mental health consequences. This rapid review therefore aimed to determine how the pandemic and its associated challenges may affect the mental health of BC's children, including those who may be disproportionately harmed. The overarching goal was to inform and assist policymakers to support all children in BC during COVID-19 — and beyond.Our systematic review identified one relevant original study on the mental health consequences of previous pandemics and five systematic reviews on the mental health consequences of natural disasters for children. The findings showed dramatic increases in rates of anxiety, posttraumatic stress, depression and behavioural challenges compared to rates typically found in the general population of children. Other literature suggests that some groups may also be disproportionately affected, including children from socioeconomically disadvantaged families and those who have faced extreme or cumulative adversities. Racism may contribute to Asian-Canadian children facing added hardships. Indigenous children may also be particularly disadvantaged given the cumulative adversities associated with the legacies of colonialism. As well, children with neuro-diverse special needs such as autism spectrum disorder, fetal alcohol spectrum disorder, developmental delays or other disabilities may have greater mental health needs during the pandemic.On balance, the available research evidence suggests that BC's response to the COVID-19 pandemic must make children's mental health a high priority — ensuring that children do not experience additional avoidable adversities due to either the pandemic or the public health responses. Central to these objectives will be: providing additional necessary prevention and treatment services; ensuring that public investments go towards effective interventions; preventing avoidable childhood adversities including reducing socioeconomic disparities; and tracking child outcomes so that all British Columbians can see the progress. Failing to address children's mental health now will lead to greater costs in the future, if mental health problems are allowed to persist into adulthood. COVID-19 is an unprecedented public health crisis. Yet it also presents an unprecedented opportunity — to make BC a place where the social and emotional wellbeing of all children is highly valued and where children are the focus of sustained collective efforts to ensure their healthy development.