This work investigates the impact dynamics of multicomponent droplets undergoing liquid–liquid phase separation upon impact on a water pool. Using a ternary ethanol/trans-anethole/water system, a classical Ouzo-type system, we show that rapid solvent exchange and delayed oil precipitation generate a dynamically evolving heterogeneous interfacial layer that strongly modifies cavity collapse and jet formation. Ethanol rapidly diffuses into the pool, whereas trans-anethole precipitates as oil-rich microdroplets once the local composition enters the Ouzo regime. While the early cavity expansion remains inertia-dominated, the subsequent collapse exhibits a two-stage relaxation process because phase-separation-induced interfacial roughness, Marangoni stresses, and viscous relaxation suppress coherent capillary-wave focusing. Jet formation is therefore not controlled by impact inertia alone: increasing impact inertia can amplify interfacial disorder and reduce the efficiency with which cavity-collapse motion is converted into an axial jet. We further show that the size of droplets emitted from the Worthington jet is selected primarily during inertial jet formation rather than during the final pinch-off. By introducing a jet Weber number based on the jet velocity and the effective interfacial tension, we obtain a unified scaling for the emitted droplet size. The final breakup of the already formed jet remains consistent with inertial–capillary necking, whereas the macroscopic droplet-size selection is governed by how phase separation reshapes cavity collapse and inertial focusing. These findings not only advance the fundamental understanding of multicomponent impact flows but also offer valuable insights for predicting jetting behaviors in industrial scenarios.