Background <p>High infiltration of CD103⁺ tumor infiltrating lymphocytes (TILs) is associated with improved patient survival in colorectal cancer. However, the spatial distribution and clinical significance of CD103⁺ TILs in colorectal liver metastasis (CRLM) remain unclear.</p> Methods <p>This study enrolled 84 patients with CRLM who underwent simultaneous surgical resection of both primary colorectal tumors (PT) and liver metastases (LM). The abundance of CD103⁺ TILs in different intratumoral compartments were evaluated using immunohistochemistry. Additionally, multiplex immunofluorescence analysis was performed to assess CD103⁺ TIL subsets. Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomic analysis were performed to investigate the functional differences of CD103⁺CD8⁺ T cells between PT and LM using a published dataset.</p> Results <p>The presence of CD103⁺ TILs in PT did not correlate with the prognosis of patients with CRLM. Conversely, an increased infiltration of CD103⁺ TILs in LM was associated with improved survival outcomes. Notably, CD103⁺ TILs in the stromal compartments of the tumor center of LM emerged as an independent prognostic factor for CRLM patients. The majority of CD103⁺ TILs in CRLM tissues were identified as CD8⁺CD103⁺ cells, followed by CD4⁺CD103⁺ cells. scRNA-seq analysis showed that the CD103⁺CD8⁺ T cells in the PT exhibit characteristics typical of CD8⁺ cytotoxic T cells, while those in the LM display features of tissue-resident memory T cells.</p> Conclusions <p>These findings reveal the heterogeneity in the spatial distribution of CD103⁺ TILs within both PT and LM tissues. Notably, the infiltration of CD103⁺ TILs in LM serves as a prognostic biomarker for CRLM patients.</p>