Background: While surgical intervention has been the usual treatment option for leiomyomas, non-surgical methods have been gaining popularity over the years. The levonorgestrel-releasing intrauterine system (LNG-IUS) is said to be effective in alleviating the signs and symptoms brought by uterine leiomyomas. Objective: To determine the effectiveness of LNG-IUS in the treatment of uterine leiomyomas presenting with abnormal uterine bleeding. Methods: The study was conducted using the PRISMA 2020 guidelines. The literature search was performed using the following databases: Medline, Cochrane Library, PubMed, Elsevier, Embase, and Herdin. All identified studies published from January 2015 up to July 2023 were included. Titles and abstracts were screened independently by two reviewers. Data extraction and risk of bias assessment were done independently by two reviewers. Gathered information were managed using Microsoft Excel spreadsheet. Synthesis of study characteristics and findings were conducted using a descriptive narrative review. The main outcomes were uterine volume, fibroid size, menstrual blood loss or bleeding patterns, and serum hemoglobin and hematocrit levels. Secondary outcome was incidence of adverse events. Results: A total of 5 studies were included with two having low methodological quality. One before-and-after cohort study showed that the use of LNG-IUS is effective in reducing menorrhagia with improvement in hematologic parameters. There is no change, however, in uterine volume. Another cohort study showed that the intervention is safe with low incidence of severe adverse events (0.5% in 595 patients). A comparative cohort study showed that LNG-IUS significantly decreased uterine volume and fibroid size, and a good alternative for treatment of heavy menstrual bleeding, as compared to intramuscular progestogen. Another before-and-after cohort study showed a significant decrease in uterine volume in women given LNG-IUS, but not in the control group. Finally, one comparative cross-sectional study showed that LNG-IUS did not effectively reduce heavy bleeding in 32.3% of patients, compared to laparoscopic hysterectomy, which was was 100% effective. Conclusion The use of LNG-IUS resulted in reduced menstrual bleeding and improved hematologic parameters after treatment. LNG-IUS was more effective compared to other hormonal treatments. However, when compared to laparoscopic hysterectomy, LNG-IUS was less effective in managing heavy bleeding. The incidence of adverse events reported in the studies was low.