Aims and objectivesTo develop a smartphone application‐based dietary self‐management program for haemodialysis patients and to examine its effects on biochemical indicators, self‐efficacy and quality of life.BackgroundLack of dietary management in haemodialysis patients can lead to serious complications such as oedema, hyponatremia, hyperkalaemia, hypertension, uraemia and eventually death; however, studies using smartphone applications for dietary self‐management in haemodialysis patients are rare.DesignA prospective, single‐blind, randomised, controlled design with repeated measures was followed with 75 haemodialysis patients at a haemodialysis centre. Data were collected from 10 January 2017–6 May 2018. The study applied the Consolidated Standards of Reporting Trials statement.MethodsThe 8‐week smartphone application‐based dietary self‐management program was developed through collaboration with a haemodialysis equipment company. The experimental group took this program while the control group took an 8‐week general program. Study variables were serum phosphorus, potassium and albumin, self‐efficacy and quality of life. They were measured at pretest, and 8 weeks and 12 weeks after the programs, and analysed using two‐way repeated measures analysis of variance.FindingsThe smartphone application‐based program significantly improved serum phosphorus, potassium, self‐efficacy and quality of life over time compared with the general program. There was no significant difference in albumin level changes between the groups.ConclusionsThe smartphone application‐based dietary self‐management program is an opportune and effective nursing intervention to lower serum phosphorus and potassium levels in haemodialysis patients over time. Trial registration was performed on www.cris.nih.go.kr (KCT0005366).Relevance to clinical practiceHaemodialysis patients can easily use the smartphone application to manage their diet anytime and anywhere. They can get real‐time feedback and solutions to prevent haemodialysis complications. Nurses can provide tailored high‐quality care based on an individual's lifelog data from the smartphone application.