There have been many reported applications of magnetorheological fluids but very few in combinations with the textile structures. Increasing the stiffness of magnetorheological fluid contained in a fabric by applying a magnetic field has considerable potential in engineering applications. In this work, we have used a spacer (three dimensional) fabric to contain the magnetorheological fluid and then investigated the changes in the stiffness value of the composite material by applying magnetic field using neodymium-iron-boron permanent magnets. Compression tests were performed at different temperatures with and without the application of a magnetic field. It was observed that the stiffness properties of the magnetorheological fluid-filled spacer fabric were increased significantly upon the application of the magnetic field at ambient temperature; however, a decrease in the stiffness value of the magnetorheological-spacer fabric composite was observed when the tests were carried out at higher temperatures. A considerable increase in the thermal conductivity of the magnetorheological fluid-containing spacer fabric was obtained under the influence of an applied magnetic field.