Non-covalent, dye-mediated interactions between organo-montmorillonites (''organo-clays'') and a chitosan-based polyelectrolyte are exploited for highly effective and fast removal of different, industrially-important anionic dyes (singleazo, double-azo, anthraquinone) from aqueous solutions. The addition of only 10 wt% of polyelectrolyte to a conventional organo-clay results in a 100% increase in absolute dye uptake capacity, an acceleration of dye uptake kinetics by up to 500%, and the flocculation of large, easily-separable sorbent aggregates. These substantial improvements in adsorption performance are driven by the mediating effect of the anionic dyes (acting as electrostatic mediator between the positively-charged polyelectrolyte chains and organo-clays), enabling the formation of true hybrid sorbent structures without the need for covalent crosslinking chemistry. The dye-mediated sorption and hybrid formation mechanism is further evidenced by structural and chemical characterization of the hybrid sorbents (small angle XRD, IR mapping) as well as by analysis of dye sorption kinetics according to the intraparticle diffusion model. Importantly, the organo-clay/polyelectrolyte hybrid system provides a highly interesting adsorbent for the treatment of dye mixtures. Our study shows that structurally different anionic dyes localise at different sites within the hybrid structure (organo-clay intergallery spaces vs polyelectrolyte/organo-clay interface), enabling the simultaneous adsorption of different dyes with high efficiency. Consequently, the total uptake capacity for dye mixtures was 50% larger than that of individual dyes, demonstrating the enormous potential of the hybrids for industrial wastewater purification, where dye mixtures are ubiquitous.