Abstract : Colorectal carcinoma (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer-related mortality worldwide. Despite advancements in screening and therapy, the rising incidence of CRC among younger populations highlights the need for novel prognostic markers. Mast cells (MCs), key components of the tumor microenvironment, may play a crucial role in CRC progression. This retrospective study analyzed 125 patients with histologically confirmed CRC who underwent radical tumor resection with lymph node dissection. Peritumoral stromal mast cell counts (MCCs) were evaluated using CD117 (c-Kit) immunohistochemical staining. Associations between MCCs and clinicopathological parameters—including tumor grade, stage, metastasis, lymphovascular invasion (LVI), and perineural invasion (PNI)—were statistically assessed. High stromal MCCs were significantly associated with higher histological grade, advanced tumor stage, presence of distant metastases, lymph node involvement, LVI, and PNI (p < 0.001). Moreover, increased MCCs correlated with higher mortality rates. No significant association was found between MCC and patient age, sex, or tumor location. Elevated mast cell infiltration in the peritumoral stroma is a significant independent predictor of poor prognosis in CRC. CD117-based immunohistochemical evaluation of stromal MCCs may serve as a useful adjunct for prognostication and individualized treatment planning in CRC management.