<p>The biological heterogeneity between left- and right-sided colorectal cancer (CRC) poses a significant clinical challenge and the underlying regulatory mechanisms remain elusive. As an emerging hallmark of cancer, the contribution of circadian rhythm disruption (CRD) to this side-specific heterogeneity is unclear. By integrating single-cell and spatial transcriptomic analyses, this study shows that tumor cells in right-sided CRC exhibit significantly higher CRD scores and identifies the emergence of a NONO-positive tumor-cell subpopulation (NONO⁺ TC) as a key molecular feature of this phenotype. Spatial analysis further confirms that this NONO⁺ TC forms a tightly co-localized microenvironment with fibroblasts in situ. Notably, cell–cell communication analyses indicate that NONO expression does not augment the signal-sending capacity of tumor cells but instead reprograms them into highly efficient signal receivers. These augmented incoming signals predominantly originate from the more pro-tumorigenic myofibroblastic cancer-associated fibroblast (myCAF) subtype, indicating that NONO⁺ TC are particularly sensitive to malignant stromal inputs. In conclusion, our study delineates the dual role of NONO as both a circadian regulator and a pro-tumorigenic signaling hub. By enhancing tumor-cell reception of CAF-derived signals, NONO links CRD to the formation of NONO⁺ TC niches and a malignant microenvironment in right-sided CRC, providing new mechanistic insight into the spatial heterogeneity of tumors.</p>