AimsTo examine the information needs of breast cancer patients during the initial phase of treatment and to analyse the factors that influenced these needs.BackgroundProviding comprehensive and timely information during early breast cancer treatment is crucial for informed decision‐making and effective coping. Healthcare providers must address these needs to enhance patient support and improve outcomes.DesignA cross‐sectional study was reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.MethodsA total of 123 post‐mastectomy patients were selected through purposive sampling and completed the Thai version of the Sri Lankan Information Needs Assessment Questionnaire‐BC (SINAQ‐BC). Direct associations between demographic data and information needs were analysed descriptively, while bivariate analysis and linear regression were used to identify significant predictors of information needs.ResultsThe findings revealed that patients exhibited high overall information needs (224.7/260.0), with the greatest demand focused on physical care, treatment and diagnosis. In contrast, needs related to disease specifics and psychosocial care were less prominent. A total of 94 respondents (76.4%) expressed a particularly high demand for information regarding physical care. Education level was identified as an influencing factor, accounting for 7.7% of the variance in information needs among women with breast cancer.ConclusionsPatients with higher education levels had significantly greater information needs. Nursing staff should provide customised information packages that are tailored to the participants' education levels. Further testing of the Thai version of the SLINQ‐BC would also be warranted.Implications for Patient CarePatients are increasingly expected to manage their own care even as medical treatment grows more complex and technical. Nursing staff can contribute to the care of patients by being ready to evaluate, monitor and address breast cancer patient's individual information needs in the early stage of treatment based on factors such as educational level.Patient or Public ContributionNo patient or public contribution because the nature of the study's design, data analysis and writing did not require patient or public contribution.