Chemotherapeutic agents often lack specificity, intratumoral accumulation, and face drug resistance. Targeted drug delivery systems based on nanoparticles (NPs) mitigate these issues. Poly (lactic-co-glycolic acid) (PLGA) is a well-studied polymer, commonly modified with aptamers (Apts) for cancer diagnosis and therapy. In this study, silybin (SBN), a natural agent with established anticancer properties, was encapsulated into PLGA NPs to control delivery and improve its poor solubility. The field-emission scanning electron microscopy (FE-SEM) showed spherical and uniform morphology of optimum SBN-PLGA NPs with 138.57±1.30nm diameter, 0.202±0.004 polydispersity index (PDI), -16.93±0.45mV zeta potential (ZP), and 70.19±1.63% entrapment efficiency (EE). The results of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) showed no chemical interaction between formulation components, and differential scanning calorimetry (DSC) thermograms confirmed efficient SBN entrapment in the carrier. Then, the optimum formulation was functionalized with 5TR1 Apt for active targeted delivery of SBN to colorectal cancer (CRC) cells in vitro. The SBN-PLGA-5TR1 nanocomplex released SBN at a sustained and constant rate (zero-order kinetic), favoring passive delivery to acidic CRC environments. The MTT assay demonstrated the highest cytotoxicity of the SBN-PLGA-5TR1 nanocomplex in C26 and HT29 cells and no significant cytotoxicity in normal cells. Apoptosis analysis supported these results, showing early apoptosis induction with SBN-PLGA-5TR1 nanocomplex which indicated this agent could cause programmed death more than necrosis. This study presents the first targeted delivery of SBN to cancer cells using Apts. The SBN-PLGA-5TR1 nanocomplex effectively targeted and suppressed CRC cell proliferation, providing valuable insights into CRC treatment without harmful effects on healthy tissues.