Objective Palliative care improves outcomes for patients with thoracic cancer; however, limited evidence exists for the benefits of this approach for caregivers. This study aimed to advance understanding of the experiences of palliative care described by bereaved caregivers. Methods Fifteen adult caregivers completed semi-structured interviews following prior participation in a randomised controlled trial of early referral to palliative care versus discretionary referral to palliative care. Interviews explored caregiver experiences of palliative care delivery. Interview transcripts were thematically analysed. Results Four related themes about the experiences of palliative care were identified, each of which required sufficient time between palliative care first contact and death: 'relationship building'; 'clear communication and information'; 'access to practical support'; and 'access to psychosocial support'. The core category underpinning these themes was palliative care facilitates caregiver preparedness. Caregivers noted that palliative care played a critical role in preparing them for the future and described a sense of practical and emotional 'relief' associated with the support services made available to them. Conclusion Our findings emphasise that palliative care can have a positive impact on caregivers' preparedness for providing the care needed by thoracic cancer patients and that this can improve the experiences of both caregivers and patients.