Background/Objectives: Ulcerative colitis (UC) has a higher risk of developing colorectal polyps and colorectal cancer (CRC) than non-UC individuals. The aim of the study was to explore the risk factors for coexisted colorectal polyps in patients with UC, especially for coexisted colorectal adenoma. Methods: Patients diagnosed with UC who were admitted to our hospital between January 1, 2015, and December 31, 2022 were enrolled in the study. Patients’ data including demographic data, smoking history, alcohol consumption history, disease related parameters, were retrospectively collected through the Electronic Medical Record System. Results: A total of 549 patients with UC were enrolled, among whom, 261 patients were with colorectal polyps. Within the polyp group, 54 patients had adenomatous polyps. Seven patients were diagnosed with CRC. Multivariate logistic regression revealed age ≤ 40 years, disease duration >10 years, severe disease activity, and non-biologic treatment were risk factors for colorectal polyps in patients with UC; while age > 40 years, disease duration > 10 years, a chronic relapsing disease course, and larger polyps size were risk factors for adenomatous polyps in UC patients; and age > 40 years, disease duration > 10 years, and the presence of polyps were risk factors for CRC in patients with UC. Conclusions: UC patients with a junior age, long disease duration, severe disease activity, and non-biologic treatment are likely to have colorectal polyps. While patients with a senior age, long disease duration, a chronic relapsing disease course, and larger polyp size should be screened for adenomatous polyps, and with senior age, long disease duration, and the presence of polyps should be screened for CRC.