Key Inclusion Criteria: * Maximum age for inclusion is 30 months. * Participant has stable health in the opinion of the investigator and as confirmed by medical history and laboratory studies with no acute or chronic hematologic, renal, liver, immunologic, or neurologic disease (other than Canavan disease). * Participant has biochemical, genetic, and clinical diagnosis of Canavan disease: * Elevated urinary NAA and * Biallelic mutation of the ASPA gene determined at Screening or documented in the participant's medical history. * Active clinical signs of Canavan disease * Participant is up to date on all immunizations per local guidelines Key Exclusion Criteria: * Tests positive for total anti-AAV9 antibodies determined by enzyme-linked immunosorbent assay (ELISA). * Received prior gene therapy or other therapy (including vaccines) involving AAV. * Participant is receiving high-dose therapy with immunosuppressants. * Participant has significantly progressed Canavan disease characterized as: * Presence of continuous/constant decerebrate or decorticate posturing, * Recurrent status epilepticus, or * Recalcitrant seizures that do not respond while on 3 or more anti-epileptic medications