This study aimed to assess impact erythritol and whey protein isolate (WPI) impact on the physical characteristics of untempered, high-protein (12/16/20/24% (w/w) of protein) white chocolates without the saccharose addition. Surfacial properties were analysed from colour coordinates, advancing and receding contact angles, apparent surface free energy and roughness. Rheological and mechanical properties, melting characteristics and water activity were also determined. Larger WPI additions facilitated greater hydrophobicity in the samples and demonstrated a smoothing effect. The mechanical characteristics, resistance to melting and shelf life were enhanced by the higher whey protein addition; however, the colour parameters were slightly affected. The samples with the higher WPI concentrations produced a continuous, more densely packed and three-dimensional solid network as visualized by the confocal microscopy, which showed the variations in their microstructures. Both compounds demonstrated an anti-blooming effect that allowed to skip tempering, reduce manufacturing costs and improve nutritional quality of resulting white chocolates.