Antimicrobial drug resistance is gradually increasing throughout the globe, and there is practically no newer antimicrobial agent coming soon. Plant secondary metabolites are well known for their various biological activities, and there are few studies targeting mangrove plants. Thus, in this study, we aim to assess the effectiveness of the ethanolic extract of the flowers of Avicennia marina, a commonly found mangrove species in coastal regions, against multi-drug resistant (MDR) microorganisms. The study focused on evaluating the extract's antibacterial activity against Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Escherichia coli (MDR), Klebsiella sp. (MDR), Acinetobacter sp. (MDR), Pseudomonas sp. (MDR). The results of the study demonstrated that the flower extracts of Avicennia marina exhibited noteworthy antimicrobial properties against all the tested MDR microorganisms. The plant contains several bioactive compounds, such as flavonoids, tannins, and alkaloids, which are believed to contribute to the observed antimicrobial effects. These findings indicate that Avicennia marina flowers could serve as a valuable natural source for developing antimicrobial agents that could combat drug-resistant bacterial infections. However, future studies should focus on evaluating the efficacy and safety of this extract in live organisms (in vivo) to determine its potential as a new drug for treating resistant infections.