Micro-slit fabrication of more than 1000 microns thick workpieces using the ECDM process is a complicated task since the ejection e ciency to remove the adhered particle dissolved from the workpiece in the electrolyte decreases with a higher depth of cut. Here micro-slit fabrication of more than 1200 µm thickness was carried out with magnetic eld application on the ECDM. The magnetic eld induces MHD convection on the electrolyte ow around the tool, which creates vorticity on the electrolyte. The centrifugal force created by the uid when it rotates under MHD convection removes the material at a higher depth of cut. The machining performance in terms of maximum slit-cut thickness improves with increasing the magnetic eld strength up to the optimum level because it induces the centrifugal force on the bubble, which enhances the gas lm formation and discharge frequency. The experiments were conducted to fabricate a micro-slit with Taguchi L18 design and observe the effect of voltage, concentration, magnetic strength, and feed rate on MRR and width overcut. The magnetic eld contributes signi cantly to the machining rate and overcut improvements. The metaheuristic algorithms, i.e., particle swarm optimization, differential evolution, and TLBO, applied and compared the optimal results of response parameters. The results reveal that the optimum value of MRR and WOC are the same, but the time and the iterations necessary to reach the optimal solution differ.