Cranial closing wedge osteotomy (CCWO) is a functional stabilization technique for cranial cruciate ligament (CrCL) ruptures. This biomechanical study aimed to evaluate the influence of CCWO on the stability of the stifle joint. Eighteen Beagle stifle joints were divided into two groups, Control and CCWO. The stifle joints were then analyzed using a six-degree-of-freedom robotic joint biomechanical testing system. The joints were subjected to 30 N in the craniocaudal (CrCd) drawer and proximal compression tests and 1 Nm in the internal-external (IE) rotation test. Each test was performed with an extension position, 135 degrees, and 120 degrees of joint angle. The stifle joints were tested while the CrCLs were intact, then transected. In the drawer test, the CCWO procedure, CrCL transection, and stifle joint flexion increased CrCd displacement. The CCWO procedure and CrCL transection showed an interaction effect. In the compression test, the CCWO procedure decreased, and CrCL transection and stifle joint flexion increased displacement. In the IE rotation test, CCWO, CrCL transection, and stifle joint flexion increased the range of motion. Therefore, CCWO was expected to provide stability against compressive force, but it does not contribute to stabilities in the drawer and rotational tests. Particularly in the CCWO-treated stifle joint, instability during the drawer test worsened with CrCL transection. In other words, performing the CCWO procedure when CrCL function is present is desirable for the stabilization of the stifle joint.