Magnetorheological elastomer (MRE) is known for its field-sensitive shear modulus and damping property when it is exposed to a magnetic field. It has a great potential for the development of vibration reduction devices. Many research, mostly in mechanical engineering, have been focused on different kinds of vibration absorbers and vibration isolators, however few research addresses its potential in base isolation system in civil engineering application. The objective of this paper is to pilot the design and experimental testing of a novel device, an adaptive MRE base isolator, for the development of smart base isolation system. A large-scale design of the novel device with unique laminated structure of steel and MR elastomer layers is adopted. Detailed procedures on designing such adaptive base isolator are introduced. An innovative design on the magnetic circuit, with aim to provide strong and uniform magnetic field to the multi-layer MRES, is proposed to incorporate into the device design. Experimental investigation is conducted to examine its behavior under various cycling loadings when it is applied with different current inputs. Experimental results indicated that the force increase and the stiffness increase of the novel device are about 45% and 37%, respectively. To conclude, the MR elastomer base isolator will be a promising candidate to facilitate the development of adaptive base isolation system for civil structures.