Oxidative stress can upset the antioxidant balance and cause accelerated aging including neurodegenerative diseases and decline in physiological function. Therefore, an antioxidant-rich diet plays a crucial role in healthy aging. This study aimed to identify and quantify mushrooms with the highest ergothioneine content through HPLC analysis and evaluate their anti-aging potential as a natural antioxidant and antisenescence in HT22 cells. Among the 14 evaluated mushroom species, Lentinula edodes (LE), shiitake mushroom contains the highest ergothioneine content and hence was used for the in-vitro studies. The cells were preincubated with ethanolic extract of ergothioneine-rich mushroom and the equimolar concentration of EGT on t-BHP-induced senescence HT22 cells. The extract was analyzed for its free radical scavenging properties using DPPH and ABTS methods. Then, the neuroprotective effect was conducted by measuring the cell viability using MTT. Senescence-associated markers and ROS staining were also analyzed. Our results revealed that a low dose of t-BHP reduces cell viability and induces senescence in HT22 cells as determined through β-galactosidase staining and expressions of P16INK4a, P21CIPL which are the markers of cellular senescence. However, the pretreatment with ethanolic extract of LE for 8 h significantly improved the cell viability, reversed the t-BHP-induced cellular senescence in the neuronal cells, and reduced the reactive oxygen species visualized through DCFH-DA staining. These results suggest that ergothioneine-rich mushroom is a potential candidate for anti-aging exploration through the elimination of senescent cells.