Background: A clinical decision support tool may improve recognition of hidradenitis suppurativa (HS) and reduce diagnosis delay. Objective: To develop and initially validate a clinical decision support to predict diagnosis of HS and distinguish it from cutaneous abscess of the axilla, groin, perineum, and buttock. Methods: This was a retrospective, cross-sectional analysis between January 2012 and June 2017 (development set) and July 2017 and March 2019 (validation set). We used an electronic records sample of 56 million patients from the Explorys database to identify patients with an ambulatory visit associated with either HS or cutaneous of the axilla, groin, perineum, and buttock. The outcome was predicted probability of HS diagnosis. Results: Development set included 7,974 patients with mean age of 41.4 years, who were predominantly female (66%) and white (62%). Validation set included 1,560 patients with similar demographic composition. Factors which were stronger independent predictors of HS included female sex (OR 2.17 [95% CI 1.96–2.40]); African American race (1.28 [95% CI 1.15–1.44]); increasing BMI (OR 1.05 [95% CI 1.05–1.06)]; history of acne (OR 3.46 [95% CI 2.83–4.23]); Down syndrome (OR 5.35 [95% CI 2.03–14.12]); and prescription for at least 7 opioid medications in the past year (OR 1.05 [95% CI 0.83–1.33]). Up to age 45 years, increasing age was a stronger predictor of HS diagnosis. The simplified model showed good discrimination (c-statistic 0.746 [SE 0.013]) and moderate calibration (calibration intercept –0.260 [SE 0.055]; calibration slope 1.142 [SE 0.076]). Conclusion: This clinical decision support tool shows good performance in predicting diagnosis of HS and distinguishing it from cutaneous abscess that involves the axilla, groin, perineum, and buttock.