Although seismic isolation is not a new technology, and it is now several decades that it is used in buildings located in earthquake prone areas of the world, the usage of this technique has not been acknowledged so much in many developing countries due to its high manufacturing and maintenance costs. Fortunately, among various seismic isolation systems, those which are based on rolling motion are much cheaper, and their employment can be encouraged easier in developing and even developed countries. As such, in this paper, a new seismic isolation system based on combination of rolling and pendulum behaviors, is proposed. This system consists of a pairs of rolling rods, each having a geometric shape of a cradle, where the point of inertia loads application is significantly distant from the rolling support. This distance causes the rolling motion to blend with pendulum motion. To evaluate the proposed system’s performance in the seismic response reduction of structures, the equations of motion were first derived for an isolated rigid body, considering the pendulum rotation angle as the independent variable in the proposed isolating system. Since the system's behavior is geometrically nonlinear, using the Lagrange equation, potential and kinetic energies of the system were derived, along with the variations of non-conservative works, to extract the differential equation for the isolated rigid body. In the second step, the differential equation which governs the motion of a single-degree-of-freedom structure located on the proposed isolation system, were developed. By numerical solution of the governing equations of motion by the modified forth order Runge-Kutta-Nistrom method through coding in MATLAB platform, the system's responses under the simultaneous effects of horizontal and vertical components of a series of selected seismic records were obtained in both isolated and non-isolated conditions, and the results were compared. The structures examined in this study include a concentrated mass system on the isolator as well as a single-story frame on the isolator, which both were subjected to three groups of high, medium, and low-frequency seismic records. Furthermore, to make sure that geometric form and size of all parts of the proposed cradle-form rolling pendulum isolator are appropriate from strength point of view, so that no yielding does not happen in them, as well as no excessive deformation, an extensive finite element analysis was also conducted. The results of seismic response analyses showed that using this isolation system can lead to significant reduction in the absolute acceleration, base shear, and story drift of the structure of around of 70% on average for almost all of the applied high, medium, and low-frequency records, although for some record this reduction is not much satisfactory. Additionally, the displacement at the isolation level averaged 40 cm. By increasing the pendulum length from 2 to 2.5 or 3 meters, the absolute acceleration of the isolated system was further reduced.