Background: The association between diverticulitis and colorectal cancer (CRC) remains unclear, though both share epidemiological characteristics. The aim of this study was to investigate whether there is higher risk for CRC after an episode of uncomplicated diverticulitis. Furthermore, in cases of CRC, we sought to determine specific tumour characteristics. Methods: This retrospective observational study includes patients with acute diverticulitis (Hinchey 0 and 1) who were conservatively treated with or without antibiotics between 2008 and 2013. Patients with endoscopic follow-up were included for analysis. Tumour characteristics of patients diagnosed with CRC during colonoscopic follow-up according to patients’ presentation of alarm symptoms were considered to be the primary endpoint. Results: A total of 977 patients were conservatively treated for an episode of acute diverticulitis, 645 of whom underwent colonoscopy during follow-up. Ten patients were diagnosed with CRC, nine of whom exhibited alarm symptoms. One patient was diagnosed with stage I disease, 4 had stage II, and 5 had stage III disease. Conclusions: This study strongly suggests that even though CRC is rare after uncomplicated diverticulitis, in cases of alarm symptoms, a colonoscopy is indicated. In cases where CRC is diagnosed, it is often advanced with a higher TNM stage and poor prognosis.