Background: Patients with acute leukaemia (AL) usually require prolonged periods of hospitalisation. The treatment and clinical symptoms may lead to patients' supportive care needs (SCNs) not being met and impairs their quality of life (QoL). Studies on QoL and SCNs among AL patients are limited. This study aimed to identify the unmet SCNs and its relation to QoL of adult AL patients in China. Methods: This multicentre cross-sectional study recruited 346 participants to complete a self-developed questionnaire, detailing demographic information and disease-related variables. A 34-item Supportive Care Needs Survey (SCNS-SF34) was used to identify unmet SCNs, and the Functional Assessment of Cancer Therapy-Leukaemia (FACT-Leu) questionnaire measured patients' QoL. Results: Unmet SCN rates for the 34 items ranged from17.6 to 81.7%. Patients' needs were high for health systems and information, but low in the sexual domain. The results reveal nine factors associated with the unmet SCNs of adult AL patients, including marital status, original residence, age, education, occupation, other diseases, chemotherapy course, disease course, and treatment stage (p < 0.05). The total score of the FACT-Leu negatively correlated with the SCNS-SF34 in the physical/daily living (r = − 0.527, p < 0.01), psychological (r = − 0.688, p < 0.01), sexual (r = − 0.170, p < 0.01), patient care and support (r = − 0.352, p < 0.01), and health systems and information (r = − 0.220, p < 0.01) domains. Conclusions: Adult AL patients exhibit a high demand for unmet SCNs, especially in the domain of health systems and information. There was a significant association between patients' unmet SCNs and QoL. Future research should develop tailored interventions to address the unmet SCNs of adult AL patients, to further improve their QoL.