AR antagonist 9 is an orally active, selective androgen receptor (AR) antagonist that inhibits cancer by disrupting the formation of AR ligand-binding domain dimers, showing potential in overcoming drug resistance in prostate cancer (PCa). Its antagonistic activity against AR has an IC50 of 0.051 μM, comparable to Enzalutamide (IC50= 0.060 μM). This compound demonstrates superior inhibitory effects on ARF876L/T877A and ARW741C mutants compared to Enzalutamide. Additionally, AR antagonist 9 possesses favorable pharmacokinetic properties, with an oral bioavailability (F) of 66.24% in rats, and significantly inhibits tumor growth in LNCaP xenograft mouse models upon oral administration. AR antagonist 9 holds promise for research in overcoming PCa resistance.