Since hypochlorite (ClO-) possesses the ability that oxidizes electron-rich objects with accompanying variations in spectroscopic features, we present here an effective strategy for generating new molecular-level probe that will be compatible for application in ClO- detection. This optical sensor has been established on a donor-pi-acceptor (D-pi-A) electronic structure derived from a pyrene derivative appended by 2-thioxo-dihydro-pyrimidine- 4,6-dione (abbreviated as Py-Pd). Specifically, it can serve as a dual-mode sensor which exhibits fluorometric and colorimetric responses to the presence of hypochlorite. The high sensitivity, selectivity, fast response time (30 s) as well as low detection limit (75 nM) have been realized. Extensive spectroscopic analyses support the oxidation cleavage of bridge C=C linkage leads to the transformation of Py-Pd to pyrene-2-carbaldehyde (Py-CHO). Such real-time imaging of hypochlorite has been also achieved in live cells and zebrafish model. In this sense, this molecular-based system can be employed as an indicator for early evaluation of optical responses of reactive oxygen species.