Purpose: Health professionals’ (HPs) knowledge of recommended guidelines for physical activity (PA) is thought to influence the advice they provide to their patients. Little is known about the knowledge or provision of PA advice by HPs working with haematological cancer patients. This study examined awareness of PA guidance, beliefs and practices in provision of advice given by UK HPs working with haematological cancer patients. Methods: Online survey including questions on awareness of PA guidance, levels of agreement/disagreement with statements related to PA in haematological cancer and reported provision of advice in practice. Open text responses sought detail regarding guidance knowledge and exampled advice given by respondents. Predictors of familiarity of guidance and provision of advice were examined. Results: Complete responses were received from 156 professionals, mostly nurses, allied HPs and doctors. Many (31%) reported knowing relevant guidance and nearly half (48.6%) reported routinely giving PA advice. Nurses and allied AHPs give advice to more patients than doctors and knowledge of guidelines among doctors was poor. Conclusion: Beliefs of haematology professionals regarding the role of PA during and after treatment for haematological cancer were generally positive. Those reporting familiarity with guidance were more likely to give advice. Misalignment exists between guidelines and advice given by professionals to their patients. Increasing knowledge of guidelines among HPs, including nurses, may lead to increased provision of PA advice and promotion of PA to more of their patients. HPs education in haematology on PA guidance tailored to professional group is needed.