Objective To construct a prognostic model for breast cancer based on cuproptosis-related long non-coding RNA (lncRNA) and to validate its efficacy. Methods The transcriptional data and clinical information of female patients with breast cancer were obtained from the Cancer Genome Atlas (TCGA) database, and cuproptosis-related lncRNAs in breast cancer were identified by Pearson correlation analysis. Breast cancer patients with complete cuproptosis related lncRNA and clinical data were taken as an overall group and were randomly divided into the training group and validation group at a ratio of 1: 1. The cuproptosis-related lncRNAs which were closely related to the prognosis of breast cancer patients were screened out by univariate Cox regression analysis and LASSO regression analysis in the training group. The multivariate Cox regression analysis was used to construct a prognostic model in breast cancer based on the above-selected lncRNAs, and then the optimal prognostic model (with the smallest AIC value) was selected based on the AIC value. Risk scores were calculated for each patient based on the optimal breast cancer prognostic model. The median risk score of the patients in the training group was used as a cut-off value to categorize all patients into high- and low-risk groups. The differentiation ability of the prognostic model was validated by survival curves and subgroup survival analysis. The accuracy of the prognostic model was validated by receiver operator characteristic (ROC) and consistency index curves. The independence of prognostic models was verified by univariate and multivariate Cox regression. The clinical utility of the prognostic model was verified by Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis of differentially expressed genes in the high- and low-risk groups, and immune infiltration analysis of patients in the high- and low-risk groups. Results The breast cancer prognostic model was constructed by 10 cuproptosis-related lncRNAs (AKT3. IT1, AL137847. 1, AL807757. 2, AC079766. 1, AL451123. 1, LINC02043, AL683813. 1, AC073127. 1, MFF. DT and AC091588. 1). The model formula was risk score = (-1. 129 216 501 573 150×expression of AKT3. IT1) + (-1. 166 095 685 256 72×expression of AL137847. 1) + (0. 729 804 497 137 164×expression of LINC02043)+ (0. 745 696 645 441 295×expression of AL683813. 1)+ (-0. 903 562 388 041 113×expression of AL807757. 2) + (1. 040 608 675 397 110×expression of AC073127. 1) + (2. 160 133 554 898 460×expression of MFF. DT) + (1. 417 144 256 517 410×expression of AC091588. 1) + (-0. 764 700 719 748 750×expression of AC079766. 1) + (-3. 608 177 447 126 010×expression of AL451123. 1). The survival curves demonstrated that patients in the high-risk group had a lower survival rate (P<0. 001). Subgroup survival analysis showed that there was significant difference in prognosis of breast cancer patients in different clinical stages, except for the M1 stage between the high- and low-risk groups (P<0. 05). ROC curves showed that the area under the curve of the model for 1-, 3-, and 5-year survival was 0. 807, 0. 739, and 0. 709, respectively. The multivariate ROC curves and the concordance index curves showed that the predictive efficacy of the risk score was superior to other clinical features. The univariate and multivariate Cox regression analysis showed that risk score was an independent prognostic feature for breast cancer. The differentially expressed genes between the high- and low-risk groups were mainly enriched in immune- and drug resistance-related pathways. Patients in the high-risk group had lower levels of immune cell and stromal cell scores and a higher abundance of M2 macrophage infiltration in comparison with patients in the low-risk group (all P<0. 05). Conclusion The breast cancer prognostic model is constructed based on cuproptosis-related lncRNAs which has good differentiation ability, accuracy, independence, and clinical utility. [ABSTRACT FROM AUTHOR]