Objectives This study aimed to compare reimbursement recommendations by the British National Institute for Health and Care Excellence (NICE) and the French National Authority for Health (Haute Autorité de Santé; HAS) for oncology new medicines indicated for the treatment of solid tumors. Methods Public assessment reports published on NICE and HAS Web sites between January 1, 2015, and December 31, 2021, describing appraisals for public reimbursement for oncology new medicines indicated for the treatment of solid tumors were searched and systematically reviewed. Biosimilars and generic drugs were excluded from the analysis. Results Overall, 119 public assessment reports published by NICE and 134 by HAS were identified, with 101 interventions assessed by both agencies. Of 101, 38 (38%) interventions received similar recommendations, 38 (38%) were recommended for different populations, and 25 (25%) were endorsed by one agency but rejected by the other. The main reason NICE would not recommend a drug was due to lack of cost-effectiveness, whereas HAS would primarily reject a drug on the grounds of insufficient clinical evidence. Conclusion The major divergence between agencies is the key criterion used for reimbursement recommendations. NICE mainly considers cost-effectiveness, whereas HAS primarily focuses on the clinical value of interventions. This contributes to the variability in reimbursement recommendations and leads to differential access to oncology new medicines indicated for the treatment of solid tumors among patients in France, and England and Wales. Highlights Both the National Institute for Health and Care Excellence (NICE) and the National Authority for Health (Haute Autorité de Santé; HAS) have established formal health technology assessment (HTA) processes and offer universal public health care coverage. However, both agencies diverge in the weight given to different elements of evidence during HTA evaluations. NICE uses cost-effectiveness as key criterion for recommendations on drug reimbursement, while HAS mostly limits its assessment to clinical value. For oncology new medicines indicated for treating solid tumors between 2015 and 2021, recommendations differed 62% of the time between NICE and HAS, primarily due to the distinct key decision-making criteria each HTA agency uses. For 4 interventions not endorsed by NICE, HAS saw these drugs as providing a substantial enhancement in clinical value over existing treatments, potentially providing an edge in price negotiations. Conversely, NICE deemed these drugs as not delivering adequate value for money in comparison with current therapies. A key difference between the 2 agencies is HAS’s insistence on methodological rigor in efficacy results, compared with NICE’s more flexible approach, considering descriptive efficacy results in cost-effectiveness modeling.