Herein, we have reported the highly effective use of the Knoevenagel condensation reaction to synthesize organoselenium containing quinoline-based probe. The probe was characterized by Nuclear Magnetic Resonance and Infra-Red spectroscopy and mass spectrometry. The probe selectively detects KO2 with high sensitivity over other reactive oxygen species and biothiols. Photo-induced electron transfer process is responsible for fluorescence “turn-on” event through transformation of selenide to selenoxide. The probe reacted with KO2 in less than a second with lower detection limit (0.14μM). The probe have better anticancer potency as compared to standard drug Cisplatin.