Purpose <p>This study aimed to develop a dynamic–static combined Neiyanggong intervention for breast cancer patients undergoing chemotherapy and to evaluate its effectiveness in alleviating cancer-related fatigue, with sleep quality assessed as a secondary outcome.</p> Methods <p>A single-center, parallel-group randomized controlled trial was conducted. Seventy-two patients receiving chemotherapy were randomly allocated (1:1) to a Neiyanggong group (<i>n</i> = 36) or a control group (<i>n</i> = 36). The control group received routine treatment and nursing care. The Neiyanggong group additionally practiced a staged progressive dynamic–static Neiyanggong program based on disease-specific characteristics across three chemotherapy cycles. The Piper fatigue scale-revised (PFS-R) and Pittsburgh sleep quality index (PSQI) were assessed at baseline and after each chemotherapy cycle.</p> Results <p>A significant interaction effect was found for the PFS-R total score (<i>F</i> = 94.810, <i>P</i> &lt; 0.001, <i>η</i>² = 0.807), indicating a progressive reduction in fatigue over time in the Neiyanggong group. After the third cycle, fatigue scores were significantly lower in the Neiyanggong group compared with the control group (<i>P</i> &lt; 0.05). For the PSQI total score, significant group effects (Wald <i>χ</i>² = 31.352, <i>P</i> &lt; 0.001), time effects (Wald <i>χ</i>² = 105.524, <i>P</i> &lt; 0.001), and interaction effects (Wald <i>χ</i>² = 292.975, <i>P</i> &lt; 0.001) were identified. The Neiyanggong group showed the most notable improvements in sleep latency, sleep efficiency, and daytime dysfunction (<i>P</i> &lt; 0.001). No adverse events occurred, and adherence was high.</p> Conclusion <p>The findings suggest that the staged progressive dynamic–static combined Neiyanggong intervention is a promising non-pharmacological approach that can effectively reduce cancer-related fatigue and improve sleep quality.</p>