Background/Objectives: The present work aimed to compare the effects of the standardized dry extract from the leaves of Monteverdia ilicifolia, popularly known as “espinheira-santa”, with omeprazole in the management of dyspepsia related to gastroesophageal reflux disease (GERD). Methods: A double-blind, randomized, non-inferiority and double-dummy clinical trial was conducted. In total, 86 patients with GERD symptoms were randomized into three groups: Omeprazol (20 mg), M. ilicifolia (400 mg), or M. ilicifolia (860 mg). Capsules were provided by SUSTENTEC^®, Pato Bragato, Brazil. It was requested that the participants take three capsules before breakfast and dinner for 4 weeks. Clinical outcomes were obtained at the beginning and end of the study, with GERD symptoms (QS-GERD), the impact of heartburn symptoms on quality of life (HBQOL), and medical records. Results: Overall, 75.6% of the participants showed adherence without any differences among the experimental groups. All groups had significant reductions in both QS-GERD and HBQOL scores. Omeprazole and 400 and 860 mg of M. ilicifolia decreased the QS-GERD total scores at the endpoint compared to the baseline (Chi-square = 129.808; p < 0.0001), as well as individual item scores, such as heartburn intensity (Chi-square = 93.568, p < 0.0001) and heartburn after meals (Chi-square = 126.426, p < 0.0001). There were no differences among the experimental groups after the intervention. Conclusions: Our results suggest that capsules with a standardized dry extract from the leaves of M. ilicifolia at a dosage of 400 or 860 mg are non-inferior to omeprazole, a proton pump inhibitor.