Maintenance haemodialysis (MHD) is the use of a machine to filter wastes, salts and fluid from blood for at least 3 months to prolong the life of patients with advanced kidney failure. Although low dietary energy intake (DEI) has been observed in MHD patients, few studies have related DEI to the risk of mortality. To explore this relationship, a study included 1039 MHD patients from eight centres was conducted. DEI was assessed by three 24-h diet recalls and was normalised to ideal body weight (IBW). All-cause mortality and CVD mortality were the primary and secondary outcomes, respectively. During a median follow-up of 28 months, a U-shaped relationship was observed between DEI and all-cause or CVD mortality. The risk of all-cause mortality decreased significantly with the increase of DEI in participants with DEI <167·4 kJ/kg IBW per d (hazard ratio (HR) 0·98; 95 % CI 0·96, 1·00) and increased significantly with the increase of DEI in those with DEI ≥167·4 kJ/kg IBW per d (HR 1·12; 95 % CI 1·04, 1·20). Similarly, the risk of CVD mortality decreased with the increase of DEI in participants with DEI <152·7 kJ/kg IBW per d (HR 0·96; 95 % CI 0·93, 0·99) and increased with the increase of DEI in participants with DEI ≥152·7 kJ/kg IBW per d (HR 1·11; 95 % CI 1·04, 1·18). In summary, there was a U-shaped association between DEI and all-cause or CVD mortality, with a turning point at about 167·4 and 152·7 kJ/kg IBW per d, respectively, in MHD patients.