The Foster Youth Mental Health Act of 2023 establishes new mental health support services specifically for children in foster care and youth aging out of the system. The bill requires the federal government to fund a national navigation program with a 24-hour text line and toll-free hotline staffed by people with foster care experience who can help youth access mental health services, substance use treatment, housing, education, and other critical resources. States receiving federal foster care funding must also dedicate at least 10 percent of their spending to develop comprehensive mental health systems that include partnerships with mental health professionals, trauma-informed training for caseworkers, peer support specialists, and safeguards to protect youth privacy during treatment. The program becomes effective immediately upon enactment, though states may have up to three months to adjust their plans if they need to change state laws, and federal funding for the national navigation program begins once annual appropriations for foster care programs exceed fiscal year 2023 levels by at least $5 million.