The solar radiation-convection boundary ( T \thicksim 180 eV, n_\mathrme \thicksim 9 \times 10^22\;\rmcm^-3) marks the transition from radiative to convective energy transport, serving as a natural laboratory for hot dense plasmas. Its physical properties are crucial for stellar evolution and energy transport models, yet how electron-impact ionization (EII) is influenced by hot-dense environment effects—such as electron screening and ion correlation—remains unclear. To address this, we systematically calculate EII cross sections for C, N, and O ions under realistic solar boundary conditions, focusing on the role of environmental effects. We develop a novel computational framework that integrates hot-dense environment effects into atomic structure calculations: the Flexible Atomic Code (FAC) for atomic structure is combined with the Hypernetted-chain (HNC) approximation to capture electron–electron, electron–ion and ion-ion correlations, enabling self-consistent treatment of electron screening and ion correlation. Atomic wave functions are derived by solving the Dirac equation within the ion-sphere model, using a modified central potential that combines both free-electron screening and ion–ion interactions. EII cross sections are then computed via the distorted-wave (DW) approximation in FAC. The results demonstrate that the hot-dense environment effects significantly enhance the electron-impact ionization cross sections of C, N, and O, compared with those calculated under the free-atom model. Additionally, a notable reduction in the ionization threshold energy is observed. These effects are attributed to the overlap of atomic potentials due to strong ion coupling and the shift in bound-state energy levels caused by free-electron screening. For instance, under solar boundary conditions, the ionization cross section of C⁺ is increased by up to 50%, with the ionization threshold decreasing from about 24 eV (isolated) to 18 eV (with screening). Similar enhancements are observed for nitrogen and oxygen ions across various charge states. By establishing updated ionization cross sections for C, N, and O ions under realistic solar interior conditions, this work provides fundamental parameters for improving radiation transport models, ionization balance calculations, and equation-of-state models in stellar interiors. The results underscore the necessity of incorporating hot-dense environment effects in the calculations of atomic processes in hot dense plasmas, which is of great significance for astrophysics and inertial confinement fusion research.