Nickel-titanium (NiTi) shape memory alloy (SMA) actuated electromechanical applications are becoming widespread in many mechatronics systems. In the thermal overload electromechanical relays (EMRs), the bimetallic strips which provide one-dimensional linear motion are used for activation. In this study, the actuation of the thermal overload EMR system is provided using the NiTi SMAs with novel EMR designs instead of traditional bimetallic strips. Two different nickel-titanium shape memory alloy-actuated thermal overload relays are designed to provide thermal overload protection for varied mechatronics systems. The displacement parameter of the designs is extracted from the established constitutive model for the NiTi SMA-actuated thermal overload relay. The developed antagonistic design structures provide functionality which is convenient for the thermal overload relays. Additionally, the developed NiTi SMA-actuated thermal overload relay designs can function in varied electrical current ranges compared to the traditional bimetallic EMRs which need to be produced separately for different electrical current ranges.