Nanomedicine holds promising potential for cancer therapy, yet challenges such as low active pharmaceutical ingredient (API), nanocarrier toxicity, complex preparation processes, and a lack of targeting ability hinder clinical applications. Here, we present a versatile method for preparing DNA aptamer-based full-API nanodrugs (ICS AFANDs). This approach involves the self-assembly of FDA-approved chemotherapeutics (irinotecan), photosensitive drugs (Chlorin e6, Ce6), and the DNA molecule of the Sgc8 aptamer. DNA aptamers are firstly confirmed to not only impart solubilization and targeting ability to ICS AFANDs but also play a pivotal role in engineering and stabilizing the formation of self-assembled nanodrugs. Our method not only significantly enhances the chemotherapy effectiveness of irinotecan by 102-fold, but also improves the near-infrared (NIR) fluorescence properties and photoactivity of Ce6. Combining photodynamic therapy (PDT) and chemotherapy (CT), our ICS AFANDs achieve complete suppression of colorectal cancer growth, with only one dose and one laser treatment, all without apparent side effects. Our strategy is a versatile method for preparing carrier-free and multifunctional DNA nanodrugs for synergistic tumor therapy. The smart and efficient full-API DNA nanodrug not only broadens the scope of synergistic tumor therapy but also facilitates the practical translation of DNA nanodrugs to clinical use.