Some evidences have been provided to verify the effects of lncRNA NNT-AS1 on cancer progression. However, the crucial impacts of NNT-AS1 on the malignancy of breast cancer have not been elaborated. This study aims to detect the expression pattern and functional effects of NNT-AS1 in breast cancer. qRT-PCR analysis was applied to detect the expression of NNT-AS1 in both BC tissues and matched normal tissues. Loss of function assay was carried out to detect the effects of silenced NNT-AS1 on proliferation, metastasis and EMT process of BC cells. To understand the functional mechanism of NNT-AS1, mechanism assays were designed and performed in BC cells. Subcellular fractionation assay demonstrated that NNT-AS1 was located in the cytoplasm of BC cells. Therefore, NNT-AS1 might exert ceRNA functions in BC cells. To validate this hypothesis, we found the combination between NNT-AS1 and miR-142-3p through conducting bioinformatics analysis, RIP and luciferase reporter assays. Similarly, the combination between miR-142-3p and ZEB1 was verified. Finally, the recue assays were carried out to demonstrate the effects of NNT-AS1/miR-142-3p/ZEB1 axis on the biological behaviors of BC cells. All the above findings revealed a fact that NNT-AS1 affects breast cancer progression through modulating miR-142-3p/ZEB1 axis.