The Amazon Forest harbors one of the largest fungal diversities on the planet, occupying a wide variety of ecological niches comprising terra firme (non-flooded forest), várzea (white-water floodplains), and igapó (black-water floodplains). In this review article, we examine Amazonian fungal diversity based on three complementary approaches—culture-based surveys, in situ inventories of macrofungi, and environmental DNA/metagenomic analyses—discussing advances, limitations, and contributions to regional mycological knowledge. Subsequently, we present a critical synthesis of the potential of Amazonian basidiomycetes regarding the production of metabolites with antimicrobial activity, highlighting the main genera reported in the literature, the chemical classes involved (e.g., terpenes, steroids, quinones, and bioactive peptides), and the metabolic pathways responsible for their biosynthesis. The integration between biodiversity and bioprospecting underscores the importance of Amazonian fungi both for understanding ecological processes and for the development of new solutions to the antimicrobial resistance challenge. This work seeks to fill current gaps in the academic literature and to contribute to future strategies for the conservation and sustainable use of regional mycobiota.