Porous silicon nanoparticles (PSiNPs) as nanocarriers for anticancer drug delivery have an important potential for cancer treatments, thus the development of PSiNPs-based delivery systems with efficient loading and controlled release of therapeutic drugs is necessary. Here, we present a novel strategy of incorporating doxorubicin (DOX) into styrene-terminated PSiNPs (S-PSiNPs) via π-stacking to form DOX@S-PSiNPs nanocomposites, which have a high-loading amount of DOX molecules. In addition, pH-controlled release of DOX molecules from the as-prepared DOX@S-PSiNPs nanocomposites was also observed. After cellular internalization of DOX@S-PSiNPs, the DOX molecules could be also efficiently released in the cytoplasm of cancer cells and then translocated into cellular nuclei, which prolonged their anticancer performance, compared with free DOX molecules.