Microcyclones are fluid separation devices that utilize centrifugal forces generated by tangential fluid injection to remove fine particles from gas or liquid streams. This review synthesizes recent advances in microcyclone fundamentals, performance enhancement strategies, and applications. Electrostatic field integration improved collection efficiency from 88.3% to 96.2% for fly ash and from 46.2% to 99.1% for submicron pollen. Stereolithographic 3D printing enabled minimum channel dimensions of 0.75 mm and cut diameters as low as 0.05 μm at 5 L/min with fabrication costs of approximately $10 per device. Optimized geometries achieved classification precision of 95.94% and efficiency of 72.89% for 25 μm silica particles. Miniature hydrocyclones demonstrated 99.98% oil-water separation efficiency at 1 L/min, while virtual cyclones reduced cut-off diameters by 38.6% with only 7.3% pressure drop increase. Openable cyclone designs achieved sampling yields 1.3 times higher than unopenable alternatives. Persistent challenges include particle entrainment, clogging susceptibility, and non-linear pressure drop versus cut-size relationships. Future directions focus on device integration, refined turbulence models, and emerging applications in aerovirology and personalized air monitoring