Current research indicate that long noncoding RNAs (lncRNAs) are associated with the progression of various cancers and can be used as prognostic biomarkers. This study aims to construct a prognostic lncRNA signature for the risk assessment of Uterine corpus endometrial carcinoma (UCEC). The RNA‐Seq expression profile and corresponding clinical data of UCEC patients obtained from The Cancer Genome Atlas database. First, some prognosis‐related lncRNAs were obtained by univariate Cox analysis. The minimum absolute contraction and selection operator (LASSO) regression and the Cox proportional hazard regression method were used to further identify the lncRNA prognostic model. Finally, seven lncRNAs (AC110491.1, AL451137.1, AC005381.1, AC103563.2, AC007422.2, AC108025.2, and MIR7‐3HG) were identified as potential prognostic factors. According to the model constructed by the above analysis, the risk score of each UCEC patient was calculated, and the patients were classified into high and low‐risk groups. The low‐risk group had significant survival benefits. Moreover, we constructed a nomogram that incorporated independent prognostic factors (age, tumor stage, tumor grade, and risk score). The c‐index value for evaluating the predictive nomogram model was 0.801. The area under the curve was 0.797 (3‐year survival). The calibration curve also showed that there was a satisfactory agreement between the predicted and observed values in the probability of 1‐, 3‐, and 5‐year overall survival. On the basis of the coexpression relationship, we established a coexpression network of lncRNA‐messenger RNA (mRNA) of the 7‐lncRNA. The Kyoto Encyclopedia of Genes and Genomes analysis of the coexpressing mRNAs showed that the main pathways related to the 7‐lncRNA signature were neuroactive ligand‐receptor interaction, serotonergic synapse, and gastric cancer pathway. Therefore, our study revealed that the 7‐lncRNA could be used to predict the prognosis of UCEC and for postoperative treatment and follow‐up.