Abstract Objective To evaluate the effectiveness of a new contoured saw guide in tibial plateau leveling osteotomy (TPLO) by comparison with the conventional TPLO technique. Study design In vitro study using bone models and canine cadavers. Sample population Twenty epoxy‐resin bone models and 10 canine pelvic limbs from cadavers. Methods Tibial plateau leveling osteotomy procedures were performed on 20 bone models (10 using the contoured saw guide without a jig and 10 using the conventional jig‐assisted technique) and on 10 cadaveric limbs (five per group). Measurements included osteotomy angulation, medial cortical damage, eccentricity distance, postoperative tibial plateau angle, angular and torsional deformities, and surgical time. Data were obtained from specimen photographs and computed tomography images and then compared statistically. Results The contoured saw guide was related to improvements in bone models, with reduced osteotomy angle of inclination (0.97° vs. 3.4°, p = .038), osteotomy angle of torsion (257 vs. 2573 pixels, p < .001), and medial cortical damage (247 vs. 1866 pixels, p < .001). In cadaveric limbs, the contoured saw guide also demonstrated better performance, with reduced osteotomy angle of inclination (1.2° vs. 4.3°, p = .008) and osteotomy angle of torsion (2054 vs. 5039 pixels, p = .016). Conclusion Tibial plateau leveling osteotomy performed with the contoured saw guide achieved more precise osteotomy angulation and caused less medial cortical damage than the conventional jig‐assisted technique. Clinical significance The contoured saw guide may enhance osteotomy accuracy and minimize iatrogenic damage caused by the saw during TPLO but in this study it did not shorten surgical time.