There are few robust evaluations of disease-specific question prompt sheets (QPS) in patient-physician communication among patients with advanced cancer. To compare the patient perception of helpfulness, global evaluation, and preference for the QPS vs a general information sheet (GIS), and to examine the effect of the QPS on participants' anxiety, participants' speaking time, number of questions asked, and length of the clinical encounter. This controlled, double-blind randomized clinical trial was conducted at an outpatient palliative and supportive care clinic in a cancer center in the US. Eligible patients were 18 years or older, had a cancer diagnosis, and were undergoing their first outpatient consultation visit with a palliative care physician from September 1, 2017, to May 31, 2019. Data analysis used a modified intention-to-treat design. Data were analyzed from May 18 to June 27, 2022. QPS, a 25-item list of questions developed by expert palliative care clinicians using a Delphi process and tested among ambulatory advanced cancer patients. The control was GIS, generic information material given routinely to patients seen at the supportive care clinic. The main outcome was patient perception of helpfulness. Secondary outcomes included global evaluation and preference of QPS compared with GIS immediately after the encounter. A total of 130 patients (mean [SD] age, 58.6 [13.3] years; 79 [60.8%] female) were randomized to receive either QPS (67 patients [51.5%]) or GIS (63 patients [48.5%]). Patients considered QPS and GIS equally helpful, with no statistically significant difference (mean [SD] helpfulness score, 7.2 [2.3] points vs 7.1 [2.7] points; P = .79). The QPS group, compared with the GIS group, had a higher global positive view of the material (mean [SD] global perception score, 7.1 [1.3] vs 6.5 [1.7]; P = .03) and felt it prompted them more to generate new questions (mean [SD] rating, 7.0 [2.9] vs 5.3 [3.5]; P = .005). Of 47 patients asked their preference between the items, more participants preferred the QPS to the GIS in communicating with their physicians (24 patients [51.1%] vs 7 patients [14.9%]; P = .01) at the 4-week follow-up. No significant differences between the QPS and GIS groups were observed regarding participant anxiety, speaking time, number of questions asked, or consultation length (eg, mean [SD] anxiety rating, 2.3 [3.7] vs 1.6 [2.7]; P = .19). In this randomized clinical trial, participants perceived both QPS and GIS as equally helpful, but they had a more positive global view of and preferred the QPS. QPS facilitated generation of new questions without increasing patient anxiety nor prolonging the consultation. The findings provide support for increased adoption and integration of QPS into routine oncologic care. ClinicalTrials.gov Identifier: NCT03287492.