Tetragonia tetragonoides, commonly known as New Zealand spinach or sea spinach, is recognized for its nutritional richness and potential health benefits. In this study, we investigated the intracellular ROS scavenging activity of extracts derived from Tetragonia tetragonoides cells cultured in vitro. The extracts were evaluated for their ability to mitigate oxidative stress using fluorescence-based assays in HaCaT cells. The Tetragonia tetragonoides extracts exhibited significant intracellular ROS scavenging activity, suggesting their potential application as natural antioxidants. Further analysis revealed promising bioactive compounds within the extracts responsible for this activity. These findings highlight the potential of in vitro cultured Tetragonia tetragonoides as a valuable source of bioactive molecules for combating oxidative stress-related disorders and promoting overall health. Further exploration of its antioxidant mechanisms and isolation of active compounds could lead to the development of novel therapeutic interventions.