The spin Hall resonance effect (SHRE) characterized by a large spin Hall conductivity (SHC) holds immense promise for achieving spin logic and memory devices. However, the identification of a material capable of achieving intrinsic SHRE remains elusive. Herein, we present compelling evidence of intrinsic SHRE within the Bi-based Janus BiXY (X = S, Se and Te; Y = Cl, Br and I) monolayers through first-principles calculations and an effective Hamiltonian model. We attribute the unusual scenario to the warping effect in the Janus monolayers which induces a non-zero out-of-plane spin component, accompanied by additional Rashba degenerate points. Furthermore, we develop a comprehensive effective Rashba Hamiltonian, incorporating high order terms of k to accurately describe the intrinsic SHRE and establish the resilience of this phenomenon in the Janus monolayers. Our study presents a captivating platform for exploring intrinsic SHRE and opens up exciting avenues for the development of novel spintronic devices.