This paper presents the design and development of a biologically inspired rat robot. The robot is scaled 2.5 times the size of a female Sprague-Dawley rat. The hindlimbs are each equipped with 4 motors to control the hip, knee, and ankle rotation in the sagittal plane, and internal/external hip rotation. The forelimbs are equipped with five motors to control the scapula, shoulder, elbow, and wrist rotation in the sagittal plane, as well as abduction/adduction of the scapula. Additionally, the hands and feet of the robot are comprised of two sections, connected with a pin and torsional springs. This allows the feet to have passive compliance and conform to the ground while walking. The leg segments are based on scanned rat bones with shapes modified for ease of assembly and 3D printing. Parts are printed using PLA with internal supports for structural reinforcement. The scapula, shoulder, and hip joints are directly driven by motors. The lower joints are driven by motors using pulley-belt transmission systems to allow the motors to be mounted more proximal, reducing the legs’ inertia. This robot was developed as a physical platform to test and make predictions about how the animal and its nervous system may interact with the environment in a more realistic way than in software simulations alone.