Immunosuppressive Tregs, regulated by IKZF2 (Helios), promote tumor immune evasion and resistance to immune checkpoint therapies (ICTs). Targeting IKZF2 degradation offers a promising cancer immunotherapy approach. We developed a novel series of iso-indolinone-based glutarimides, identifying compound 55 as a potent, selective IKZF2 degrader with >90% Dmax in Jurkat cells, outperforming benchmarks DKY709 and PVTX-405. It exhibits strong selectivity over IMiD neo-substrates, favorable solubility, metabolic stability, and oral bioavailability in rodents. PK/PD studies confirmed profound, persistent IKZF2 degradation in mouse spleen and thymus after a single oral dose. As a promising early-stage tool, 55 provides a foundation for further preclinical evaluation in cancer immunotherapy.