Background: As cancer incidences rise within the Saudi population, effective pain management remains a critical component of oncological care. Analgesic adherence is vital for managing cancer-related pain, yet it is often inadequately addressed in clinical practice, leading to diminished quality of life of patients. Objectives: This study aimed to assess the level of adherence to analgesic medications among Saudi cancer patients and to identify demographic and health-related factors that may influence adherence. Methods: In a cross-sectional study at King Abdulaziz Medical City, 132 oncology patients were sampled randomly. Data were collected through an online survey incorporating demographic queries and the Morisky Medication Adherence Scale (MMAS-8). SPSS 26 facilitated the statistical analysis, with descriptive statistics and Spearman’s Rho tests determining the significance of the findings. Results: Among participants, 52.2% were married, 51.5% were unemployed, and 80.4% reported substantial social support. Health insurance was prevalent among 79.5% of patients. Low adherence was observed in 94.6% of patients, with only 0.8% showing high adherence. The primary reasons for non-adherence included forgetting (54.5%) and fear of side effects (38.6%). Age and the number of medications were significantly correlated with adherence levels, highlighting the multifactorial nature of medication adherence in this patient population. Conclusions: The research highlights a concerning level of low adherence to analgesics among Saudi oncology patients, suggesting an urgent need for targeted interventions. Strategies to improve adherence should focus on education regarding the importance of pain management and addressing patients' concerns about medication side effects and dependency, as well as personalized medication management plans to accommodate the complexities of handling multiple medications. These findings are instrumental for oncology healthcare providers to optimize pain management strategies and enhance patient outcomes.