Low-cost Synthetic-Iron-Oxide-Merged-Crushers-Waste (SIOMCW) was developed as an adsorbent for phosphate remediation and found effective to adsorb ~ 80% phosphate from wastewater within 10 min of contact time, with a shaking speed of 150 ± 5 rpm, at 10 g/L dosage of adsorbent with the initial concentration 1 mg/L at room temperature and at a pH of 6.8 ± 0.3. Crusher waste (CW) was collected from the Khurda District, Odisha India, and sieved to get the geometric mean sized particle of 106 µ, washed, dried. The dried material was then coated with Fe(III) oxide using aqueous Fe(NO3)3·9H2O, again washed and dried called SIOMCW and applied for phosphate removal from wastewater. The prepared adsorbent was characterized by SEM/EDX and XRD for the surface morphology, elemental detection and chemical composition. Adsorption followed the pseudo-second-order reaction mechanism (rate constant = 1996.241 × 10−3 g mg−1 min−1). Adsorption process followed Freundlich isotherm more than Langmuir isotherm and the adsorption capacity was 0.2544 mg PO43−/g SIOMCW. D-R isotherm indicated the physisorption of the adsorption process. The film diffusion (Df = 5.5 × 10−6 cm2/s) was proved to be the rate determining step. Probable adsorption mechanism of the study was proposed.