In contrast to non-adherent planktonic cells, biofilms are groups of microbial cells attached to surfaces and encased in an extracellular matrix that exhibit significantly greater resistance to antimicrobial drugs. As a result, biofilm-based illnesses are very challenging to treat. The high level of recalcitrance that characterizes biofilm communities is caused by a variety of molecular pathways. These mechanisms include decreased growth rates, the difference in antibiotic resistance and tolerance, and the interaction of antimicrobials with components of the biofilm matrix. Each of these processes, by itself, only explains a portion of the elevated antimicrobial resistance seen in biofilms. Due to their antibacterial, antifungal, and antibiofilm properties, the metallic nanoparticles made by green synthesis utilizing medicinal plants have garnered much attention from the scientific community. Various techniques or procedures have been effectively created and put into practice to assess these pharmacological characteristics. These procedures suffer from a conspicuous lack of uniformity of the experimental circumstances, despite being mostly influenced by the standards issued by national and international regulatory authorities. Data from various study settings becomes less reproducible and comparable as a result of this circumstance. Subject-matter experts should create guidelines for the antimicrobial and antibiofilm assessment of metallic nanoparticles to reduce these issues. The disparities arising from the various experimental designs are also compiled in this review, highlighting how they affect biological activities and how they should be interpreted. To provide the groundwork for the future creation of potent antibacterial metallic nanoparticles by green synthesis, the study concludes by offering a broad perspective that necessitates in-depth experimental research.