Background/Objectives: The rational use of medicines, in accordance with the World Health Organization (WHO) guidelines, is crucial for optimizing healthcare outcomes. This cross-sectional study aimed to evaluate drug prescribing patterns and assess prescription completeness based on the WHO core drug use criteria. A comprehensive analysis was conducted at the University Clinic in the Northern region, Kingdom of Saudi Arabia (KSA). Methods: The study assessed drug prescribing patterns and examined prescription completeness by analyzing various parameters recommended by the WHO core drug use criteria. Results: Upon analyzing the 615 prescriptions, it was observed that each prescription had a mean of 2.56 prescribed drugs. Multiple medicines per prescription were prevalent in 71.4%, whereas polypharmacy was evident in 2.9%. Analgesics were the most frequently prescribed medication, accounting for 50.4% of the prescriptions, followed by supplements (31.7%), decongestants (16.1%), cough syrup (12%), and antihypertensive and diabetes treatments at 17%. Furthermore, antimicrobials were prescribed in 21.5% of the prescriptions. During the evaluation, it was found that 19.8% of the prescriptions were incomplete, lacking important information on dosing, duration, and drugs not suited to the diagnosis. Conclusions: Most of the parameters evaluated in this study were determined to fall outside the range of recommended guidelines criticized by the WHO. As a result, the implementation of efficient intervention programs, such as education initiatives, is recommended to enhance the practice of rational drug use. Contribution: This study highlights the importance of improving prescription indicators at the national level, focusing on both medication prescribing characteristics and prescription quality as a practice.