Iron oxide-silica nanocomposite synthesized by one-pot co-precipitation method was evaluated for its applicability as sorbents for removal of toxic species like inorganic metal ions (UO₂²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺) and cationic dyes (MB and R6G) from aqueous streams at room temperature. The detailed structural analysis revealed the formation of crystalline iron oxide core with amorphous silica shell. The zeta potential measurements of surface charge helped in assessing the applicability of the sorbents. The magnetic property of the sorbent, as evaluated from magnetic measurements helped in its easy separation from solution using external magnetic field. The high porosity and large surface area of sorbent contributed to its excellent sorption efficiency. The efficiency of magnetic nano-composites was analyzed with respect to sorption kinetics (rate and kinetics order), initial concentration of toxic species (equilibrium conditions) and weight of sorbent. The optimum pH for uptake was in the range of 5–6. Extensive modelling of sorption data helped in getting an insight to the mechanism of metal ion sorption. The selectivity towards uptake of MB (MB) as opposed to that of Rhodamine 6G (R6G) was quite intriguing and detailed studies were carried out to understand this. Since the bare nanosorbent showed no selectivity in sorption of metal ions, modification was carried out to enhance selectivity with respect to uranyl ion.