•The single-site mean-field formalism for segregation in multicomponent alloys is outlined.•Surface segregation is calculated for the (111) surface in austenitic steel and FeMnCrCoNi alloy.•In both alloys, strong surface segregation of Ni and anti-segregation of Cr is predicted. Segregation modelling in multicomponent random alloys within the single-site mean-field approximation is considered. As an example, the surface segregation in austenite Fe70Cr20Ni10 and equimolar Fe20Mn20Co20Cr20Ni20 random fcc alloy towards the (111) facet is calculated using ab initiomultiple scattering technique in the coherent potential approximation (CPA). The results show a very similar trend in both alloys: relatively strong surface segregation of Ni and strong anti-segregation of Cr. However, in the case of Fe70Cr20Ni10, the reversal of the surface enrichment from Ni to Fe is observed at 1750 K, while the surface of FeMnCoCrNi is Ni-rich up to 2500 K.