Introduction Day surgery is defined as the admission of a patient and discharge after the surgical procedure within the same day. It is becoming increasingly popular as it provides multiple advantages for the health care system and patients, including better resource utilization in the form of decreasing the cost, increasing the number of patients served, a reduction in the waiting list length, and preservation of hospital beds for complex advanced cases. Internationally, patients' admission rate after a planned day surgery was found at 1.5%. Etiologies for day surgery conversion vary among studies, 75% of which were labeled as potentially preventable. As patients are admitted, the benefits of day surgery decrease. Aim This study aimed to measure the unanticipated admission rate of day surgery while evaluating the reasons for admission in King Fahad Specialist Hospital, Buraydah, Qassim, Saudi Arabia. Materials and methods This is a retrospective review study in which all medical records of patients admitted and operated as day surgery from January 1, 2015 to February 28, 2021 in King Fahad Specialist Hospital in Buraydah, Qassim region in Saudi Arabia were evaluated. Variables collected included baseline characteristics such as age, gender, body mass index (BMI), chronic diseases, surgical history, operation name, complications, and causes of conversion. Results A total of 6,771 day surgery cases were found from January 1, 2015 to February 28, 2021. Of them, 231 cases were converted to inpatient admission, and the prevalence of conversion was 3.4%. The most common cause of conversion was pain (35.1%) followed by postoperative care (16%), need of antibiotics (12.1%), and bleeding (8.2%); most of these cases were associated with laparoscopic cholecystectomy. Furthermore, laparoscopic cholecystectomy (36.4%), hernia repair (12.1%), and pilonidal sinus excision were the most frequent surgical intervention. Conclusion The day surgery conversion rate was minimal in this study (3.4%). Pain, postoperative care, and the need for antibiotics were the most common reasons for conversion. Continuous monitoring of day surgery conversion rate and causes will all help the institution to gain the maximum benefits of day surgeries.