This study assessed the effectiveness of potassium sorbate, citric acid, sodium bicarbonate, and calcium chloride as pre- and postharvest treatments to enhance resistance in Lirica RZ (F1 Hybrid) sweet peppers against Colletotrichum gloeosporioides. Potassium sorbate was the most effective at inhibiting fungal growth, followed by citric acid, while sodium bicarbonate and calcium chloride were less effective. Sweet peppers treated with potassium sorbate or citric acid showed significantly reduced anthracnose incidence, better quality preservation, lower weight loss, and delayed ripening in both the 2021 and 2022 test seasons. These treatments also improved fruit firmness and maintained higher total soluble solids (TSS) compared to untreated controls.