In this study, a multi-functional cotton fiber was prepared and investigated for the visual detection and enhanced adsorption of cadmium (Cd) ions in aqueous solutions. SI-ATRP technology was used to graft poly (glycidyl methacrylate) (PGMA) and poly (3-sulfopropyl methacrylate potassium salt) (PSMP) successively on the surface of the cotton fiber. Then, diethylenetriamine (DETA) and 5,10,15,20-tetrakis(1-methy-4-pyridinio) porphyrin tetra(p-toluenesulfonate) (TMPyP) were immobilized onto the PGMA and PSMP polymer brush, respectively, to form the Cotton-PGMA(DETA)-PSMP(TMPyP) (abbreviated as C-PD-PT) material. C-PD-PT showed enhanced Cd ion adsorption with the maximum adsorption capacity of 1.6215 mmol/g derived from the Langmuir model fitting. In addition, The C-PD-PT material exhibited simple visual detection of Cd ions with a remarkable color change from brownish to green. A linear relationship between the light absorbance of C-PD-PT-Cd (C-PD-PT adsorbed with Cd ions) and the initial concentrations of Cd ions was established, which would be used for the fast determination of Cd ion concentrations in aqueous solutions.