Adenomyosis is a gynaecological problem that impacts women's quality of life by causing dysmenorrhea, chronic pelvic pain, and menorrhagia. The search continues for the best medical treatment for symptomatic adenomyosis. This systematic review and meta-analysis investigated the role of dienogest, an oral progestin, in reducing pain and bleeding associated with adenomyosis. Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, MEDLINE, Scopus, and Web of Science were searched in January 2024. The primary outcome was pain scores for dysmenorrhea, whereas secondary outcomes were chronic pelvic pain (CPP), uterine volume (UV), and menorrhagia. One comparison was performed comparing outcomes in symptomatic adenomyosis before and after treatment with dienogest. Pooled analysis of included studies reported a statistically significant reduction of dysmenorrhea pain score after dienogest treatment (mean difference -5.86 cm on a 10-cm visual analogue scale, 95 % CI -7.20 to -4.53, I2 = 97 %). Regarding chronic pelvic pain, a meta-analysis of included studies showed a significant decline in pain after treatment (standardized mean difference -2.37, 95 % CI -2.89 to -1.86, I2 = 60 %). However, uterine volume did not differ significantly after treatment (mean difference -4.65 cm³, 95 % CI -43.22 to 33.91). Menorrhagia was improved significantly after treatment (Peto odds ratio 0.07, 95 % CI 0.03 to 0.18). In conclusion, dienogest seems to be effective in controlling painful symptoms and uterine bleeding in women with adenomyosis at short and long-term therapy.