More US children and adolescents today die from firearms than any other cause, and many more sustain firearm injuries and survive. The clinical and economic impact of these firearm injuries on survivors and family members remains poorly understood. Using 2007-21 commercial health insurance claims data, we studied 2,052 child and adolescent survivors compared to 9,983 matched controls who did not incur firearm injuries, along with 6,209 family members of survivors compared to 29,877 matched controls, and 265 family members of decedents compared to 1,263 matched controls. Through one year after firearm injury, child and adolescent survivors experienced a 117 percent increase in pain disorders, a 68 percent increase in psychiatric disorders, and a 144 percent increase in substance use disorders relative to the controls. Survivors' health care spending increased by an average of $34,884-a 17.1-fold increase-with 95 percent paid by insurers or employers. Parents of survivors experienced a 30-31 percent increase in psychiatric disorders, with 75 percent more mental health visits by mothers, and 5-14 percent reductions in mothers' and siblings' routine medical care. Family members of decedents experienced substantially larger 2.3- to 5.3-fold increases in psychiatric disorders, with at least 15.3-fold more mental health visits among parents. Firearm injuries in youth have notable health implications for the whole family, along with large effects on societal spending.