Purpose <p>We sought to determine if the rate of cefazolin use for antimicrobial prophylaxis could be increased in elective surgical patients with a reported β-lactam antibiotic allergy with the use of a simplified questionnaire and without of skin testing.</p> Methods <p>We conducted a quality improvement intervention at University Health Network, Toronto, ON, Canada by adapting a novel allergy assessment tool, the Modified Allergy Clarification for Cefazolin Evidence-based Prescribing Tool (ModACCEPT), which uses history alone to determine the safety of using cefazolin among patients with a self-reported β-lactam antibiotic allergy (SRBA) in the absence of skin testing. Prior to this, we performed knowledge dissemination campaigns to the surgical divisions and anesthesiology to communicate the safety of this approach. We used an interrupted time series analysis to determine the impact of the intervention on the proportion of patients with SRBA receiving cefazolin perioperative prophylaxis.</p> Results <p>Historic electronic data determined the stable rate of cefazolin administration within the institution at 28% (March 2019) among patients with self-reported β-lactam antibiotic allergy. A recalculation of the baseline confirmed a shift to 62% at the time of project team formation (August 2020). After surgical-program-wide educational efforts and implementation of the ModACCEPT tool, we observed special cause variation, with a new baseline stability at 84% for the primary hospital site. Notably, there was also a small improvement in the rate of cefazolin use, from 20% to 46%, at a second hospital site in the network.</p> Conclusions <p>Adaptation of a two-question β-lactam antibiotic allergy assessment tool, along with targeted education, was associated with significantly increased rates of cefazolin use for perioperative prophylaxis in patients with a β-lactam antibiotic allergy label.</p>