The quality and performance of products produced by the electrical discharge machining process mainly affected by the integrity of the machined surface. The recent development in the various assisted EDM process used magnetic field and mixed-phase dielectric fluids need to examine their effect on surface integrity. Therefore, in the present study, an investigation has been performed to evaluate the effect of a magnetic field and different dielectric conditions mainly liquid, liquid–air and liquid–argon gas mixture on surface integrity in the machining of AISI 304 steel. Their effect on surface and sub-surface features such as surface roughness, micro-cracks, recast layer thickness, heat affected zone, chemical and phase transformation have been compared. In addition, the effect of variation in the pressure of air/argon gas in the mixed phased dielectric and magnetic flux density on surface integrity have also been evaluated. The reactive nature of oxygen from air and inertness of argon gas mixed in liquid dielectric governed the heat supply and heat transfer rate into the discharge crater. The results showed that the assistance of air and argon gas narrow down the surface cracks by 55% and 72%, respectively, as compare to liquid dielectric. The magnetic field reduced the surface roughness by 18% and 32% in the air-assisted EDM and argon gas-assisted EDM, respectively. However, the combined assistance of magnetic field and air/gas increased the thickness of recast layer and HAZ as compared to EDM using liquid dielectric and without assistance of magnetic field.