Long noncoding RNAs (lncRNAs) play a significant role in the occurrence and development of malignant tumours. However, ceRNAs, which are significantly associated with the prognosis of breast cancer (BC), need to be further investigated. Therefore, the current study aimed to investigate the effect of the lncRNA DDX11-AS1 on BC progression. Bioinformatics analysis via a public microarray revealed that DDX11-AS1 was upregulated in BC. The above findings were verified via RT-qPCR analysis of BC tissues. Additionally, our study revealed that the expression levels of DDX11-AS1 increased with increasing pathological grade and lymph node metastasis. Furthermore, DDX11-AS1 knockdown markedly inhibited the proliferation, migration and invasion abilities of BC cells. Mechanistically, DDX11-AS1 could prevent the degradation of MTDH in BC via competitively binding with miR-30c-5p, which could act as a tumour promoter factor. Additionally, miR-30c-5p was downregulated and MTDH was upregulated in BC cells and tissues. The promoting effect of DDX11-AS1 on BC cells was enhanced by miR-30c-5p silencing and reduced by treatment with MTDH inhibitors. Collectively, the above results suggest that the DDX11-AS1/miR-30c-5p/MTDH axis could be associated with the progression of BC and that DDX11-AS1 could be a potential biomarker and therapeutic target for BC.