Background: Pain is one of the most common and dreaded sequelae of cancer, occurring in approximately 55% of patients. The experience of pain takes a toll on the patients’ quality of life. However, many patients do not receive adequate pain management. This study aimed to determine the prevalence of pain, its severity, and the adequacy of pain management among cancer patients in the Philippines. Methods: A cross-sectional study was conducted at a representative cancer center in the Philippines, enrolling 351 cancer patients. Pain severity was assessed using the Brief Pain Inventory-Short Form (BPI-SF) Filipino. The BPI evaluates pain severity and its impact on daily functioning (pain interference). To ascertain the adequacy of pain control, the pain management index (PMI) was calculated by subtracting the subtracting the severity of pain reported by the patient from the type of analgesic treatment received. Logistic regression analysis was conducted to evaluate the factors associated with worst pain and adequacy of pain management. Data were analyzed using Stata version 16.0, with statistical significance set at p < 0.05. Results: Three hundred three cancer patients (86.3%) experienced pain. Approximately 3 out of 5 patients (n = 208) did not receive adequate pain control, and one-third of patients experienced severe pain (n = 121). Patients who reported severe pain interference (n = 110) had three times greater odds to experience severe pain (OR 3.2, 95% CI 1.82-5.61, p < 0.001). Those patients who had regular follow up were 65% less likely to experience severe pain (OR 0.35, 95% CI 0.16 – 0.78, p = 0.01). Patients who used pain medications (n = 196) were 14 times more likely to experience adequate pain management (OR 14.19, 95% CI 6.53 – 30.83, p < 0.001). Patients who were referred to pain service (n = 25) were seven times more likely to report adequate pain control (OR 6.62, 95% CI 2.50 – 17.56, p < 0.001). Conversely, those patients who reported a severe rating on total pain interference were 75% less likely to experience adequate pain management (OR 0.25, 95% CI 0.17 – 0.35, p < 0.001). Conclusions: Unexpectedly, there was a high prevalence of pain among cancer patients at a representative cancer center in the Philippines. Pain exerts a heavy toll on patients, affecting daily functioning. The undertreatment of pain discovered in this study (59% of cancer patients) is alarming. Timely pain evaluation can help identify the presence of pain and the need for appropriate use of analgesics. The assessment and management of pain is a critical component of cancer care that should not be neglected.