Background/Aims@#Immunocompromised patients with acute colonic diverticulitis are at high risk for complications and failure of non-surgical treatment. However, evidence on the comparative outcomes of immunocompromised and immunocompetent patients with diverticulitis is lacking. This systematic review and meta-analysis investigated the outcomes of medical treatment in immunocompromised and immunocompetent patients with diverticulitis. @*Methods@#A comprehensive literature search was conducted in PubMed, Embase, and the Cochrane Library. Studies comparing the clinical outcomes of immunocompromised and immunocompetent patients with diverticulitis were included. @*Results@#A total of 10 studies with 1,946,461 subjects were included in the quantitative synthesis. The risk of emergency surgery and postoperative mortality after emergency surgery was significantly higher in immunocompromised patients than in immunocompetent patients with diverticulitis (risk ratio [RR], 1.76; 95% confidence interval [CI], 1.31–2.38 and RR, 3.05; 95% CI, 1.70–5.45, respectively). Overall risk of complications associated with diverticulitis was non-significantly higher in immunocompromised than in immunocompetent patients (RR, 1.24; 95% CI, 0.95–1.63). Overall mortality irrespective of surgery was significantly higher in immunocompromised than in immunocompetent patients with diverticulitis (RR, 3.65; 95% CI, 1.73–7.69). By contrast, postoperative mortality after elective surgery was not significantly different between immunocompromised and immunocompetent patients with diverticulitis. In subgroup analysis, the risk of emergency surgery and recurrence was significantly higher in immunocompromised patients with complicated diverticulitis, whereas no significant difference was shown in mild disease. @*Conclusions@#Immunocompromised patients with diverticulitis should be given the best medical treatment with multidisciplinary approach because they had increased risks of surgery, postoperative morbidity, and mortality than immunocompetent patients.