Diabetes and cancer are two of the most common public health concerns worldwide. The complex interplay of these two conditions is a growing area of research, as patients with diabetes are at increased risk for developing cancer, and vice versa. Furthermore, both patient populations show increased risk of many communicable infectious diseases and their adverse consequences, while vaccination can play a crucial role in their prevention, improving patient outcomes. Vaccination should represent a standard part of care for patients with cancer, diabetes, and both the diseases simultaneously, including people undergoing cancer treatment or in remission. Several international guidelines provide recommendations for vaccinating people with cancer or diabetes, but the two conditions have not been specifically evaluated together. Here we present a multidisciplinary consensus position paper on vaccination in patients with cancer and diabetes. The position paper is the result of a collaborative effort between experts from the Italian Association of Medical Oncology (AIOM), Italian Association of Medical Diabetologists (AMD), Italian Society of Diabetology (SID), Italian Society of Endocrinology (SIE), and Italian Society of Pharmacology (SIF). The paper provides a comprehensive overview of the current state-of-the-art knowledge on vaccination in patients with cancer and diabetes. It discusses the importance of vaccination in preventing infections, focuses attention on the need to consider the unique challenges faced by patients with cancer and diabetes when it comes to vaccine administration, and highlights the need for coordinated care to optimize treatment outcomes. Overall, the consensus position paper provides healthcare professionals caring for patients with cancer and diabetes recommendations on the use of various vaccines, including influenza, COVID-19, HZV, and HPV vaccines, as well as guidance on how to address common concerns and challenges related to vaccine administration.