Globally, the infection with Helicobacter pylori (H. pylori) considered the most prevalent issue that causes chronic inflammation of the stomach. In this study, the phytochemical investigation of Arenga engleri (family Arecaceae) leaves extract that used to prepare the AgNPs and examined for their potential activity against H. pylori. The phytochemical results revealed the presence of different phenolic contents depending on the preliminary phytochemical screening, TPC and TFC measurements, and HPLC profiling. Besides, the percent of unsaturated and saturated fatty acids were 51.39 % and 31.47 %, respectively, based on GC/MS analysis. The as- prepared AgNPs were characterized by using UV-Vis spectroscopy, IR spectroscopy, TEM, and Zeta potential analyses. The synthesized AgNPs displayed promising anti H. pylori with MIC = 7.81 µg/mL, while the A. engleri extract showed weak activity with MIC = 500 µg/mL compared with clarithromycin MIC of 1.95 µg/mL after 3 days of incubation. In conclusion, the acids, phenolic, and flavonoid contents of A. engleri extract was used as capping agents to prepare simple, low-cost, and effective AgNPs with a particle size range of 10-26 nm that explained their high penetration towards the bacterial cell of H. pylori and destroyed it