Ailanthus excelsa is a medicinal plant with notable ethnopharmacological relevance, yet its phytochemical diversity and molecular interactions with cancer-related targets remain underexplored. This study aimed to investigate the hydroalcoholic extract of Ailanthus excelsa using an integrated experimental and computational approach. The extract was prepared by maceration and evaluated through physicochemical, phytochemical, GC–MS, molecular docking, and in silico ADMET analyses. Physicochemical evaluation demonstrated acceptable quality parameters, including pH values of 6.5 (1% solution) and 6.2 (10% solution), loss on drying of 6.67%, total ash value of 7.9%, and extractive values of 14.9% (alcohol-soluble) and 15.56% (water-soluble). Microbial analysis confirmed the absence of pathogenic microorganisms, supporting extract safety. Preliminary phytochemical screening revealed abundant phenolics and flavonoids, with moderate levels of alkaloids, saponins, tannins, and glycosides. GC–MS profiling identified 90 phytochemical constituents across a retention time range of 6.7–47.6 min. Major compounds included CC8 (12.20%), CC2 (8.85%), CC4 (6.96%), and CC7 (4.81%). Ten potent compounds were selected for molecular docking against mutant EGFR tyrosine kinase (PDB ID: 8WD4). Notably, CC1 showed the highest binding affinity (−8.2 kcal/mol), followed by CC8 (−8.0 kcal/mol). ADMET analysis revealed favorable drug-likeness (QED >0.83 for key compounds), high predicted intestinal absorption, low toxicity risk, and minimal environmental impact. Overall, the results highlight Ailanthus excelsa as a rich source of bioactive phytochemicals with promising potential to overcome EGFR-mediated drug resistance, justifying further experimental validation and lead optimization.