<p>The selective recovery of Cd(II) from complex aqueous matrices remains a challenge due to the coexistence of competing metal ions and the need for efficient and sustainable extraction systems. In this work, we investigate the task-specific ionic liquid trioctylmethylammonium thiosalicylate (TOMATS) as an extractant for Cd(II), both in conventional solvent extraction and incorporated into polymer inclusion membranes (PIMs). Liquid–liquid extraction studies showed quantitative Cd(II) extraction under optimal chloride conditions, with high selectivity over Cu(II), Pb(II), and Ni(II). The effect of chloride was demonstrated to be critical, promoting the formation of extractable CdCl₃⁻​ and CdCl₄²⁻​ complexes. When TOMATS was incorporated into cellulose triacetate-based PIMs, efficient Cd(II) extraction was maintained, and the membranes exhibited good stability and reusability over multiple extraction–stripping cycles. Spectroscopic characterization (FT-IR, EDXRF) supported an extraction mechanism involving ion-pair formation between TOMATS and chloro-cadmium complexes, without ligand exchange by the thiosalicylate group. Overall, this study highlights TOMATS as a selective and reusable extractant for Cd(II), and demonstrates the viability of TOMATS-based PIMs as a simpler and more sustainable alternative to liquid–liquid extraction for Cd(II) removal from natural waters.</p>