Hypopharyngeal cancer (HPC) is associated with the worst prognosis of all head and neck cancers and is typically identified in an advanced stage at the time of diagnosis. While oxidative stress might contribute to the onset of HPC in patients using tobacco or alcohol, the extent of this influence and the characteristics of HPC cells in advanced stage remain to be investigated. In this study, we explored whether HPC cells survived from necrotic xenograft tumors at late stage would display increased tumor resistance along with altered tolerance to oxidative stress. The remnant living HPC cells isolated from a late-stage xenograft tumor, named FaDu Ex-vivo cells showed stronger chemo- and radio-resistance, tumorigenesis, and invasiveness compared to parental FaDu cells. FaDu Ex-vivo cells also displayed increased angiogenic ability after re-transplantation to mice visualized by in vivo near infrared-II (NIR-II) fluorescence imaging modality. Moreover, FaDu Ex-vivo cells exhibited significant tumor-initiating cells (TICs) related properties accompanied by a reduction of the level of reactive oxygen species (ROS), which was associated with up-regulation of transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). Interestingly, inhibition of Nrf2 by the RNA interference and the chemical inhibitor could reduce TICs related properties of FaDu Ex-vivo cells. Oxidative stress potentially initiates HPC, but elevation of Nrf2-associated antioxidant mechanisms would be essential to mitigate this effect for promoting and sustaining the stemness of HPC at the advanced stage. Current data suggest that the antioxidant potency of advanced HPC would be a therapeutic target for the design of adjuvant treatm.