Purpose The prevalence of obesity and the number of bariatric surgeries are increasing in Saudi Arabia. Studies evaluating nutritional knowledge, especially in Middle Eastern countries, are limited. Therefore, this study was conducted to examine the general and postbariatric nutritional knowledge related to dietary recommendations among patients undergoing bariatric surgery. Patients and Methods In a cross-sectional study, 112 patients aged 18–65 years, of both genders, were recruited from the Surgical Clinics at King Abdul-Aziz University Hospital in Jeddah, Saudi Arabia. Patients' knowledge pertaining to general nutrition and consumption after bariatric surgery was assessed in relation to dietary recommendations, using a preoperative questionnaire. Results The mean general nutrition knowledge score was 42 of a maximum of 85 points (50%). Approximately 40% and 60% of patients were classified with a low and medium level of nutritional knowledge, respectively. Postbariatric nutritional knowledge among patients was very low (mean: 16/81 points). The level of education was correlated with patients' body mass index (p=0.045) and the general nutritional knowledge total score (p=0.05). Conclusion General and postbariatric nutritional knowledge among Saudi bariatric patients is currently insufficient. A multicenter study involving a larger sample size with different sociodemographic characteristics is warranted to confirm these findings. The purpose of such a study would be to determine the nutritional knowledge of patients undergoing bariatric surgery and inform the implementation of educational strategies.