Alternanthera sessilis and Alternanthera tenella are two edible plants that are frequently encountered in the tribal region of Rampachodavaram, Andhra Pradesh, India. These plants offer many nutritional benefits and have positive impacts on health. The primary aim of this study is to assess the phenolic composition of both plants by extracting methanol from the whole plant using a cold maceration method. The extract of Alternanthera sessilis demonstrated the highest concentration of polyphenols, measuring 61.45 mg GAE/g of dry extract weight. Both extracts shown efficient free radical scavenging action on DPPH. However, the Alternanthera tenella extract had the lowest determined IC50 value of 8.53 μg mL-1. LC-ESI-QTOF-MS/MS analysis detected a total of 24 phenolic compounds, which were further grouped into their respective classes such as phenolic acids (6), flavonoids (9) including flavonols and flavones, diterpenoids (2), coumarins (1), saponins (1), alkaloids (3) and glycosides (1). Notably, the Alternanthera sessilis extract exhibited the highest proportion of Betaine, a compound belonging to the betalanins class commonly found in plants of the Amaranthaceae family.