Abstract As a copper (Cu) transport ATPase, ATP7B plays an important role in maintaining Cu homeostasis in the body and its dysfunction is associated with retinal disease. How ATP7B dysfunction and the subsequent Cu overload induce retinal damage, however, are unknown. Here, we show that atp7b−/− homozygous zebrafish larvae are insensitive to light stimulation, with a reduction in retinal cells but normal like morphological phenotypes. Additionally, a series of differentially expressed genes are unveiled in atp7b−/− mutated larvae, which enrich in photo-transduction, structural constituent of eye lens, sensory perception of light stimulus, oxidative phosphorylation, and ATPase activity. Moreover, we show the Cu accumulation in retinal cells in atp7b−/− mutated larvae, which results in endoplasmic reticulum (ER) stress and retinal cell apoptosis and subsequent retinal defects. The integral data in this study demonstrate that atp7b mutation leads to Cu accumulation in zebrafish retinal cells and the consequence ER stress and retinal cell death. These data may give some possible hints to explain retinal disease occurred in the Cu dysregulation syndromes Wilson’s disease with ATP7B mutation.