Endoscopic resection is typically performed for early T1 stage colorectal cancer (T1 CRC). Additional surgery is subsequently recommended based on pathological findings; however, the current criteria may result in overtreatment. The present study aimed to re-examine the reported risk factors for lymph node (LN) metastasis in T1 CRC and develop a prediction model using a large multi-institutional dataset. In this retrospective study, the medical records of 1,185 patients with T1 CRC who underwent surgery between January 2008 and December 2020 were investigated. Slides pathologically re-assessable for additional risk factors were re-examined. A total of 251 patients with inadequate data were excluded, and 934 patients were randomly assigned at a ratio of 3:1 to the training and validation datasets. In the univariate analysis, left-sided CRC (P=0.003), deep submucosal invasion depth (P=0.005), poor histological grade (P=0.020), lymphatic invasion (P