Purpose The objectives of this study were to compare the unmet supportive care needs (SCN) of caregivers and describe the 10 most frequent of them according to various cancer settings: phase of cancer care pathway (i.e., treatment vs. follow-up), cancer site (i.e., breast, digestive, or lung cancer), and cancer status (i.e., metastatic vs. non-metastatic). Methods Participants completed a self-reported questionnaire to assess their unmet SCN (SCNS-P&C). According to their cancer settings, non-parametric ANOVA or Mann–Whitney tests were performed to compare the SCNS-P&C scores. The prevalence of caregivers with unmet SCN was described using percentages. Results Among 583 participants, 516 caregivers (88.5%) completed the SCNS-P&C questionnaire. Most patients had digestive (47.3%), non-metastatic cancer (67.6%) and were recruited during the follow-up phase (56.2%). The results revealed no significant difference in SCNS-P&C scores according to cancer settings except for caregivers of patients with metastatic cancer, who reported more unmet SCN related to health care service and information needs. The more qualitative item per item analysis seems to indicate the existence of five frequently unsatisfied SCN across situations, especially concerns about the recurrence and reduction of stress in patients, with variable ranking among the most unmet SCN. Conclusion Although there was no significant difference in unmet SCN scores between medical settings, examining the prevalence of unmet SCN helps identify the issues to focus on when supporting caregivers and developing dedicated consultations or interventions for them.