Introduction Drug-related problems (DRPs) affect the health outcomes of patients during hospitalization. We sought to analyze the clinical pharmacist-documented interventions among hospitalized patients in the cancer hospital in Qatar. Methods A retrospective analysis of electronically reported clinical pharmacist interventions of patients admitted to cancer units at Hamad Medical Corporation, Qatar was conducted. Extracted data was based on an overall 3-month follow-up period; March 1–31, 2018, July 15–August 15, 2018 and January 1–31, 2019. Categorical variables were expressed as frequencies and percentages, while continuous variables were expressed as mean ± standard deviation (SD). Results A total of 281 cancer patients with 1354 interventions were included. The average age of the study participants was 47 years (SD ± 17.36). The majority of the study population was females ( n = 154, 54.80%). The prevailing pharmacist intervention was the addition of a drug therapy ( n = 305, 22.53%), followed by medication discontinuation ( n = 288, 21.27%) and the addition of a prophylactic agent ( n = 174, 12.85%). This pattern was similar across all subgroups (i.e., gender, age, ward), except for the urgent care unit, where an increase in medication dose was the third highest frequently identified intervention ( n = 3, 0.22%). The two medication groups associated with the majority of interventions were the anti-infective and fluid/electrolyte agents. Most of the interventions documented were in the oncology ward (73.19%), while the urgent care unit had the least documented interventions (1.62%). Conclusions Our analysis showed that clinical pharmacists can effectively identify and prevent DRPs among hospitalized cancer patients.