Kaolin is an aluminosilicate mineral with low adsorption and degradation ability for organic dye molecules. Herein, to improve its adsorption properties, kaolin was composited with goethite, which is known to absorb and degrade dye molecules. The kaolin/goethite composites were synthesized via a simple low-temperature method. Specifically, a ferric ion solution and sodium hydroxide were consecutively added to commercial kaolin, and the mixture was aged at 40 °C for seven days. The synthesized composites were characterized by means of XRD and SEM, and their use in the adsorption and degradation of methylene blue dye was investigated. The ability of the composites to degrade organic matter was evaluated using the advanced oxidation process method. A mineralogical and morphological analysis of the synthetic products showed that goethite and the composites were synthesized on the surface of kaolin. However, the presence of amorphous iron material was detected in both types of products. The adsorption capacity of goethite, kaolin, and the kaolin/goethite composites for methylene blue was 54.64, 14.68, and 50.76 mg/g, respectively. The adsorption process fitted the Langmuir isotherm model with a correlation efficiency higher than 0.999. Goethite and the composites degraded effectively methylene blue upon addition of hydrogen peroxide. Although the composites exhibited lower adsorption and degradation ability than goethite, their structure was more stable, which was confirmed by the more efficient readsorption of methylene blue after the degradation process compared with kaolin and goethite. This study demonstrates that the adsorption and catalytic ability of kaolin can be modified by compositing with goethite.