The analysed samples made of high-alloy, austenitic X2CrMnNi16-7-4.5 steel were produced using electron beam powder bed technology (PBF-EB/M). The surface quality of all additively manufactured parts is very poor by nature. Therefore, a post-processing step is required to improve their surface integrity. Although a variety of post-processing technologies exist, not all are suitable for additively manufactured parts as they are geometrically limited or too labour- and/or time-intensive. For this reason, this study focuses on two polishing techniques that are particularly suitable and efficient for treating such parts. These are particle blasting (PB) and plasma electrolytic polishing (PEP). The analysed samples were treated either with the two-step PEP process or with the combination of PB and PEP. The surface roughness of the samples was measured before and after the treatment using the MahrSurf confocal microscope. The material removal rate, MRR, was also determined. The final surface quality depends very strongly on the initial surface roughness, therefore the PBF-EB/M parameters were also optimised to improve the surface quality of the samples in as-build condition. The surface roughness of the investigated non-optimised and optimised samples in the as-built condition varied between Sq = 50.8 μm and Sv = 243.0 μm and Sq = 40.0 μm and Sv = 167.3 μm. While the PBF-E/M parameter optimisation effect on the surface roughness parameter Sq is not significant, it resulted in smaller and fewer defects in subsurface region of the samples was well as lower absolute height of the highest pit Sv. In addition, a lower final surface roughness was achieved in the samples with optimised PBF-EB/M parameters compared to the non-optimised samples. The analysed samples were treated with PB for a total of 15 min and finally with PEP for 30 min. The process parameters were 9000 RPM, 7000 RPM and 4000 RPM for 5 min each for PB and DC voltage at U = 330 V and/or U = 300 V and an electrolyte temperature of 75 °C for PEP. The resulting surface roughness was Sq = 15.7 μm and Sv = 188.8 μm and Sq = 37.8 μm and Sv = 137.8 μm for the samples with non-optimised and optimised PBF-EB/M parameters, respectively. The greatest reduction in surface roughness was achieved for the sample with non-optimised PBF-EB/M parameters, which was polished using the two-step PEP process. However, the total duration of the treatment was 60 min, while the sample with the optimised PBF-E/M parameters was PEP-treated for only 30 min. The final surface roughness of the sample with non-optimised PBF-E/M parameters that was polished using a combination of PB and PEP was Sq = 21.0 μm and Sv = 248.5 μm.