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Aim: To explore the clinical factors associated with pathologic complete response (pCR) for locally advanced rectal cancer (LARC) patients treated with neoadjuvant chemoradiotherapy (nCRT) and develop a web‐based dynamic nomogram. Methods: Retrospective analysis of patients with examination confirmed LARC from 2011 to 2022. Patients from the Union Hospital of Fujian Medical University were included as the training cohort (n = 1579) and Zhangzhou Hospital of Fujian Medical University as the external validation cohort (n = 246). Results: In the training cohort, after nCRT, 350 (22.2%) patients achieved pCR. More stomas were avoided in pCR patients (73.9% vs. 69.7%, p = 0.043). After a median follow‐up time of 47.7 months (IQR 2–145) shown OS (5‐year: 93.7% vs. 81.0%, HR = 0.310, 95%CI: 0.189–0.510, p < 0.001) and DFS (5‐year: 91.2% vs. 75.0%, HR = 0.204, 95%CI: 0.216–0.484, p < 0.001) were significantly better among patients with pCR than non‐pCR. Multivariable Logistic analysis shown pCR was significantly associated with Pre‐CRT CEA (HR = 0.944, 95%CI: 0.921–0.968; p < 0.001), histopathology (HR = 4.608, 95%CI: 2.625–8.089; p < 0.001), Pre‐CRT T stage (HR = 0.793, 95%CI: 0.634–0.993; p = 0.043), Pre‐CRT N stage (HR = 0.727, 95%CI: 0.606–0.873; p = 0.001), Pre‐CRT MRI EMVI (HR = 0.352, 95%CI: 0.262–0.473; p < 0.001), total neoadjuvant therapy (HR = 2.264, 95%CI: 1.280–4.004; p = 0.005). Meanwhile, the online version of the nomogram established in this study was publicized on an open‐access website (URL: https://pcrpredict.shinyapps.io/LARC2/). The model predicted accuracy with a C‐index of 0.73 (95% CI: 0.70–0.75), with an average C‐index of 0.73 for the internal cross validation and 0.78 (95% CI: 0.72–0.83) for the external validation cohort, showing excellent model accuracy. Delong test results showed the model has an important gain value for clinical characteristics to predict pCR in rectal cancer. Conclusions: Patients with pCR had a better prognosis, including OS and DFS, and were independently associated with Pre‐CRT CEA, histopathology, Pre‐CRT T/N stage, Pre‐CRT MRI EMVI, and TNT. A web‐based dynamic nomogram was successfully established for clinical use at any time. [ABSTRACT FROM AUTHOR]