A tandem cleavage of carbon-carbon and carbon-nitrogen bonds in imidazo[1,2-a]pyridines and imidazo[1,2-a]quinolines is reported in the presence of eosin Y and visible light. The ring opening occurs under ambient conditions through singlet oxygen insertion, bond cleavage and CO2 elimination, and produces N-(pyridin-2-yl) amides and N-(quinolin-2-yl) amides in high yields. The reaction shows good versatility, and does not require strong external oxidants and additives.