T-cell acute lymphoblastic leukemia (T-ALL) is the most prevalent malignancy in children. Long non-coding RNAs are being found to have relevance to the pathogenesis of pediatric T-ALL. However, the function of cyclin-dependent kinase inhibitor 2B anti-sense RNA 1 (CDKN2B-AS1) in pediatric T-ALL progression and chemoresistance has not been illuminated. The levels of CDKN2B-AS1, miR-335-3p and tumor necrosis factor receptor-associated factor 5 (TRAF5) were assessed by quantitative real-time PCR. Cell proliferation and the 50% inhibitory concentration (IC50) value were detected using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetr-azolium assay. Cell cycle and apoptosis were evaluated by flow cytometry. Western blot analysis was performed to measure protein expression. Targeted interactions among CDKN2B-AS1, miR-335-3p and TRAF5 were determined by the dual-luciferase reporter and RNA immunoprecipitation assays. Animal studies were conducted to observe the function of CDKN2B-AS1 in vivo. Our data indicated that CDKN2B-AS1 was highly expressed in pediatric T-ALL peripheral blood mononuclear cells and cells, and high CDKN2B-AS1 level was associated with adriamycin (ADR) resistance. CDKN2B-AS1 depletion hindered T-ALL/ADR cell proliferation and cell cycle progression, and promoted cell apoptosis and ADR sensitivity in vitro. Moreover, CDKN2B-AS1 knockdown repressed tumor growth and enhanced ADR sensitivity in vivo. CDKN2B-AS1 sequestered miR-335-3p, and CDKN2B-AS1 depletion exerted regulatory effect in T-ALL/ADR cell progression by up-regulating miR-335-3p. TRAF5 was a direct target of miR-335-3p, and TRAF5 mediated the regulation of miR-335-3p in T-ALL cell behaviors. Furthermore, CDKN2B-AS1 positively modulated TRAF5 expression through sponging miR-335-3p. The current work suggested that CDKN2B-AS1 knockdown repressed the progression and enhanced ADR sensitivity of pediatric T-ALL at least partly through targeting miR-335-3p/TRAF5 axis, highlighting a promising therapeutic target for the treatment of pediatric T-ALL patients.