AbstractGenerally, studies of the critical current I_c are necessary if superconductors are to be of practical use, because I_c sets the current limit below which there is a zero-resistance state. Here, we report a peak in the pressure dependence of the zero-field I_c, I_c(0), at a hidden quantum critical point (QCP), where a continuous antiferromagnetic transition temperature is suppressed by pressure toward 0 K in CeRhIn₅ and 4.4% Sn-doped CeRhIn₅. The I_c(0)s of these Ce-based compounds under pressure exhibit a universal temperature dependence, underlining that the peak in zero-field I_c(P) is determined predominantly by critical fluctuations associated with the hidden QCP. The dc conductivity σ_dc is a minimum at the QCP, showing anti-correlation with I_c(0). These discoveries demonstrate that a quantum critical point hidden inside the superconducting phase in strongly correlated materials can be exposed by the zero-field I_c, therefore providing a direct link between a QCP and unconventional superconductivity.