The synthesis of the two novel 1,8-naphthalimideruthenium conjugates Ru-Nap-NO2 and Ru-Nap-NH2 and their photophysical evaluation upon interaction with DNA is reported. Significant changes were seen in both the absorption and emission spectra upon interaction of both conjugates with DNA, from which large binding constants were determined. Moreover, highly efficient DNA cleavage was observed upon irradiation for 5 min, during which supercoiled DNA was converted to nicked and linear DNA by RuNap-NH2.