Singularity avoidance steering laws for control momentum gyros (CMGs) and variable speed control moment gyros (VSCMGs) are addressed. The proposed methodology is based on a constrained optimization by minimizing a cost function which consists of a singularity index and a kinetic energy term. The new singularity avoidance law prevents CMG/VSCMG clusters from encountering a singularity condition. It turns out that the proposed optimal CMG steering law is in a general form including the conventional null motion solution. Also, an optimal steering law is developed to overcome the wheel speed saturation problem during the operation of VSCMG clusters. The performance of the new steering law is demonstrated through a simulation study with a three-parallel single-gimbal CMG/VSCMG cluster.