Due to its predictable self-assembly and structural stability, structural DNA nanotechnology is considered one of the main interdisciplinary subjects encompassing conventional nanotechnology and biotechnology. Here we have fabricated the mucin aptamer (MUC1)-conjugated DNA nano-ring intercalated with doxorubicin (DNR-DOX) as potential therapeutics for breast cancer. DNR-DOX exhibited significantly higher cytotoxicity to the MCF-7 breast cancer cells than the controls, including DOX alone and the aptamer deficient DNA nano-ring (DNR) with doxorubicin. Interactions between DOX and DNR were studied using spectrophotometric measurements. Dose-dependent cytotoxicity was performed to prove that both DNR and DNR were non-toxic to the cells. The drug release profile showed a controlled release of DOX at normal physiological pH 7.4, with approximately 61% released, but when exposed to lysosomal of pH 5.5, the corresponding 95% was released within 48 h. Owing to the presence of the aptamer, DNR-DOX was effectively taken up by the cancer cells, as confirmed by confocal microscopy, implying that it has potential for use in targeted drug delivery.