<p>In this work, excess Cr₂O₃ powders (by adding 25%, 50%, and 75% Cr atoms relative to an equiatomic composition, respectively) are added to obtain equiatomic high entropy carbide ceramics with a single-phase rock salt structure via the technology of carbothermal reduction and spark plasma sintering. The effects of excess Cr₂O₃ addition on the solid solubility of Cr, elemental distribution, and mechanical properties of (Ta₁Ti₁V₁Cr_<i>x</i>)C₄ ceramics are investigated in detail. With the increase of excess Cr₂O₃ addition, the Cr atom ratio of the synthesized powders increases from 7.0 at.% to 14.5 at.%, where Cr partially participates in the solid solution reaction to form (V,Cr)C solid solutions, while the remainder continues to exist in the form of Cr₂O₃ powders. During spark plasma sintering, (V,Cr)C solid solutions dissolve into the (Ta,Ti)C solid solutions, resulting in a single-phase structured ceramics with dense and uniform element distribution. When the addition of excess Cr₂O₃ is 25% and 50%, Cr atoms reach the equiatomic ratio in the as-sintered specimens. And the increase in Cr solid solubility is mainly attributed to the residual Cr₂O₃ powders reacting with free carbon to form Cr₃C₂, which then dissolves into (TaTiVCr)C ceramics during high-temperature sintering. Additionally, with the increase of Cr solid solubility, the nano-hardness of (TaTiVCr)C ceramics is improved, reaching up to 34.75&#xa0;GPa with 50% excess Cr₂O₃ addition, owing to the lattice distortion and solid solution strengthening caused by the relatively small atomic radius of Cr.</p> Graphical abstract <p></p>