Objective To evaluate the efficacy of a surgical safety checklist (SSC) in reducing perioperative and postoperative complications. Study design Before‐and‐after intervention study. Animals Client‐owned dogs (n = 633) and cats (n = 44). Methods Consecutive surgeries were enrolled in the study. The “before” phase consisted of 267 surgeries performed without an SSC (SSC−) followed by 75 SSC− surgeries in which a trained observer was in the operating room to detect possible complications. An SSC was then implemented in the operating rooms during 1 week. The “after” phase consisted of 58 surgeries in which a safety checklist (SSC+) and an observer were used and 277 SSC+ surgeries without an observer. Complications were prospectively recorded when witnessed by the observer, and all other perioperative complications were retrospectively recorded from veterinary records and client telephone communication. Results There were more perioperative and postoperative complications when surgeries were performed without an SSC (140/342 [40.9%; 95% CI, 35.7%‐46.4%]) than there were when surgeries were performed with an SSC (98/335 [29.3%; 95% CI, 24.4%‐34.4%]; P = .002). Surgical checklist use, presence of an observer, American Society of Anesthesiologists score, and anesthesia time were all independently associated with the odds of complications. Conclusion Implementation of an SSC in an academic teaching hospital decreased the odds of perioperative and postoperative surgical complications. Clinical significance This study supports the use of an SSC to prevent surgical complications in veterinary teaching hospitals.