Context: Prognostic information is considered important for advanced cancer patients and primary informal caregivers to prepare for the end of life. Little is known about discordance in patients’ and caregivers’ prognostic information preferences and prognostic perceptions, while such discordance complicates adaptive dyadic coping, clinical interactions and care plans. Objectives: To investigate the extent of patient-caregiver discordance in prognostic information preferences and perceptions, and the factors associated with discordant prognostic perceptions. Methods: We conducted secondary analyses of a cross-sectional study (PROSPECT, 2019–2021). Advanced cancer patients (median overall survival ≤12 months) from seven Dutch hospitals and caregivers completed structured surveys (n = 412 dyads). Results: Seven percent of patient-caregiver dyads had discordant information preferences regarding the likelihood of cure; 24%–25% had discordant information preferences regarding mortality risk (5/2/1 year). Seventeen percent of dyads had discordant perceptions of the likelihood of cure; 12%–25% had discordant perceptions of mortality risk (5/2/1 year). Dyads with discordant prognostic information preferences (P < 0.05) and dyads in which patients reported better physical functioning (P < 0.01) were significantly more likely to perceive the one-year mortality risk discordantly. Conclusion: Physicians should be sensitive to discordant prognostic information preferences and prognostic perceptions among patient-caregiver dyads in advanced cancer care.