<p>Bimetallic nanoparticles represent a paradigm shift in catalyst design, where the synergistic interaction between the two metals often results in performance that surpasses the mere sum of their individual contributions. This mini-review delves into the fundamental origins of this synergism, unravelling how electronic effects (e.g., d-band center shifts) and geometric effects (e.g., alloy, core-shell, and intermetallic structures) collectively contribute to the enhancement of the activity, selectivity, and stability. The predictive power for rational catalyst design, moving beyond traditional trial-and-error approaches using Density functional theory (DFT) will be discussed. The review further surveys accessible synthetic strategies, from co-reduction and solvothermal to biogenic methods, highlighting their role in tailoring nanostructures. Applications across catalysis, from selective hydrogenation and CO₂ reduction to SERS, are categorized by metal combinations (precious-precious, precious-earth-abundant, earth-abundant-earth-abundant), providing a roadmap for targeted catalyst development. Finally, perspectives on overcoming key challenges in scalability, mechanistic understanding via operando spectroscopy, and the future integration of AI and ML to accelerate the discovery of next-generation bimetallic catalysts have also been presented.</p> Graphical abstract <p>Bimetallic catalytic systems generated via combinations of noble and earth-abundant metals for the synthesis of a variety of heterostructures and their diverse applications. </p> <p></p>