Chimeric antigen receptor (CAR) T cells are a major new treatment option for children, adolescents, and young adults (CAYA) patients with relapsed and refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL). Therefore, accumulating evidence from real-world experiences of CAR-T outcomes in various regions worldwide is important, particularly when comparing outcomes of patients with differing medical and ethnic backgrounds. More than 5 years have passed since tisagenlecleucel was approved in Japan. Here, we report a retrospective, multi-institutional investigation examining the association between baseline parameters and clinical outcomes. The aim was to investigate real-world experience and to better comprehend the efficacy of commercial tisagenlecleucel. A nationwide consortium called the Japan CAR-T Consortium conducted a retrospective, multicenter study of CAYA patients who received CAR-T cell treatment with commercial tisagenlecleucel. Forty-two patients with R/R B-ALL whose leukapheresis samples were shipped to Novartis for commercial tisagenlecleucel manufacture were included in the analysis. All infused patients were included in the response, toxicity, and survival analyses. The best overall response rate was 93%. The 1-year overall survival and event-free survival (EFS) rates after infusion were 82% and 56%, respectively. Twenty-seven (64%) had low disease burden (LB, defined as <5% bone marrow [BM] lymphoblasts) prior to tisagenlecleucel infusion. LB was associated with superior outcomes, with a 1-year EFS rate of 80% compared with 24% in high disease burden (≧5% BM lymphoblasts). Multivariate analysis identified an association between prior hematopoietic stem cell transplantation (HSCT) (n = 23, 55%) and superior outcomes, with a 1-year EFS rate of 75% compared with 24% for patients without prior HSCT. This first analysis of CAYA patients with R/R B-ALL undergoing treatment with commercial tisagenlecleucel in Japan reports an efficacy similar to that in clinical trials and other real-world studies and confirms that LB and prior HSCT are associated with superior EFS.