Purpose Acute diverticulitis is a common presentation to hospital emergency departments, and a significant burden on healthcare resources worldwide. Multiple studies have shown that outpatient management of uncomplicated diverticulitis is safe, yet many patients are still treated in hospital. We instituted a protocol for the outpatient treatment at our institution focusing on safety and healthcare costs. Methodology From February 2021 the new outpatient management of uncomplicated left sided diverticulitis protocol was implemented; all patients that presented through the emergency department with a computed tomography diagnosis of uncomplicated left sided diverticulitis were managed as an outpatient with oral antibiotics unless they met exclusion criteria (insulin requiring diabetes, immunosuppression, active malignancy, pregnancy or inflammatory bowel disease). This was compared to a historical comparison immediately prior. The primary outcome of interest was length of stay in hours. Results There were 106 patients in each group. The length of stay in the outpatient group was 29.7 hours less than the inpatient group (95%CI 21.9 to 37.5. P=<0.001). In a multivariable regression analysis, having adjusted for the effects of previous surgery for diverticulitis, COPD, ASA and age, patients in the outpatient cohort length of stay was 30.7 hours less compared to the inpatient cohort (95%CI 23.4 to 97.9, P<0.001). The odds of readmission were not different between the outpatient and inpatient cohorts (OR 1.49, 95%CI 0.544 to 4.07, P=0.438). Conclusion Outpatient management for uncomplicated left sided diverticulitis results in significant reduction of length of stay and did not result in an increase in readmissions.