This short review provides a concise overview of magnetic micromixers operating in the presence of nanofluids, a class of active microfluidic devices that leverage external magnetic fields to overcome the inherent mixing limitations of laminar flow at low Reynolds numbers. Unlike passive micromixers that rely solely on channel geometry, magnetic micromixers employ embedded or externally positioned magnetic elements, such as ferromagnetic wires, magnetic beads, or ferrofluid droplets, to induce localized chaotic advection through contactless actuation, offering tunable performance and reduced risk of contamination. Collectively, these works demonstrate that mixing efficiency can be significantly enhanced, by up to 89% in some cases, through careful optimization of magnet number, spacing, frequency, and nanoparticle volume fraction, as well as through the strategic design of microchannel geometry. However, several research gaps persist, including limited experimental validation, insufficient attention to long-term device reliability, and a lack of integrated lab-on-a-chip systems. Future directions should prioritize hybrid actuation mechanisms, smart magnetic materials, and scalable designs.