Background. Surgical site infections (SSIs) are considered to be some of the most serious postoperative health concerns among patients with diabetes mellitus (DM) who undergo coronary artery bypass graft (CABG) surgery. Objective. The purpose of this study is to identify and explore the predictors of SSIs among patients with DM after CABG surgery. Methods. A quasi-experimental study was conducted using a convenience sample of 144 adult patients who were scheduled to undergo CABG at the main referral heart institute in Amman, Jordan from September 1, 2018, through November 30, 2018. Eligibility criteria stipulated participants should be adult (43–74 years) Jordanian patients with DM who underwent CABG surgery with or without cardiopulmonary bypass (CPB) and elective or urgent CABG surgery as well as being able to read and write Arabic. Key patient demographics, health history, baseline lab work, surgical characteristics, and clinical outcomes were collected from medical records. Data were collected to spreadsheets, anonymized, and entered into statistical software for bivariate and multivariate negative binomial regression analyses. Mean and standard deviation were used to describe continuous variables, and frequencies and percentages were used to describe categorically measured variables, along with chi-squared calculations. Results. Of the 144 participants, the majority of the patients (130; 90.3%) were male (mean age, 59.66 years [SD = 9.3]). Data revealed the most significant predictors for the development of SSIs post-CABG surgery included higher body mass index (bivariate mean 32 ± 4.6, P = .028; multivariate: [1-1.186] x 100 = 18.6% times more likely to experience SSI), lower preoperative serum cholesterol level (bivariate: P = .005; multivariate: [1-0.973] x 100 = 2.7% times less likely), and higher preoperative serum blood urea nitrogen level (bivariate: P = .011; multivariate: [1-1.191] x 100 = 19.1% times more likely). Conclusions. Three key factors were found to predict the occurrence of SSIs in patients with DM undergoing CABG. These findings underscore the necessity for health care providers to adhere to and employ meticulous infection control practices when managing at-risk CABG patients.