Background: Unwanted postoperative hypothermia is an unpleasant event that can cause various complications. Objectives: As this serious complication and its provoking causes have not been investigated sufficiently, this study was designed and conducted to determine the prevalence of hypothermia and its associated factors in the post-anesthesia care unit after elective surgery. Methods: Four hundred patients undergoing elective surgeries were enrolled in the present cross-sectional research after termination of surgery and at the time of arrival at the post-anesthesia care unit of Poursina Public University Hospital. The tympanic membrane temperature was measured and recorded at the time of arrival at the post-anesthesia care unit and every 30 minutes after arrival. The required data were collected in a researcher-made checklist and analyzed after entering the SPSS software version 25. Results: Considering the 5% error, it can be said that the prevalence of hypothermia in patients undergoing elective surgery ranges from 20 to 28% at the time of arrival at the post-anesthesia care unit and 18.5 to 26% 30 minutes after arrival. Conclusions: More than a quarter of patients experienced hypothermia following elective surgery. Therefore, appropriate treatment and control measures are necessary to manage this complication, particularly in patients with predisposing risk factors and comorbidities.