As one of the most important water quality parameters, chlorophyll a is an important indicator to evaluate the degree of eutrophication of water bodies and also the main factors of primary productivity state of the oceans. The coastal zone imager (CZI) onboard the Chinese Haiyang-1C (HY-1C) satellite has an advantage observation in high temporal and spatial resolution. In this study, a chlorophyll a concentration retrieval model for CZI onboard the HY-1C satellite is developed from the in-situ measurements in the East China Sea and the South China Sea. The chlorophyll a concentration is retrieved by the model in the measured waters and compared with MODIS chlorophyll a concentration. The chlorophyll a concentration also retrieved in the Zhujiang River Estuary, Changjiang River Estuary and Bohai Bay. The correlation coefficient between the predicted value of the model and the in-situ chlorophyll a concentration is 0.774 3, the average relative error is 24.58%. The accuracy of the model is verified with the in-situ measurements with the correlation coefficient of 0.993 9 and the average relative error of 18.49%. The distribution of chlorophyll a concentration retrieved from CZI is nearly the same as that of MODIS. The chlorophyll a concentration decreases gradually from northwest to southeast and the peak value locates on the west bank of the Zhujiang River Estuary. The inversion of chlorophyll a concentration in Changjiang River Estuary and Bohai Bay accords with the actual situation. The work in this study indicates that HY-1C satellite coastal zone imager data are useful for the monitoring of coastal ocean color in China.