Significance Reactive oxygen species (ROS) play a role in signaling in immune cells, in particular in B cell activation and terminal differentiation in secondary lymphoid organs. Nevertheless, their role in B cell development in the bone marrow (BM) still remains poorly explored. TP53INP1 is a target of the tumor suppressor p53, which mediates its antioxidant activity. We report the surprising observation that chronic oxidative stress in TP53INP1-deficient mice rescues B lymphopoiesis in the BM during aging. ROS sustain IL-7R signaling in aged TP53INP1-deficient BM through maintenance of active STAT5 transcription factor, driving the expression of the B lineage Pax5 transcription factor. This work suggests that antioxidants cannot be in favor of antibody-producing cell development.