Long noncoding RNA PPP1R14B antisense RNA 1 (PPP1R14B-AS1) has emerged as a critical modulator of liver cancer and lung adenocarcinoma progression. However, the functional importance and biological relevance of PPP1R14B-AS1 in breast cancer remain unclear. Therefore, this study was designed to detect PPP1R14B-AS1 levels in breast cancer cells using qRT–PCR and elucidate the influence of PPP1R14B-AS1 on aggressive phenotypes. Furthermore, molecular events mediating the action of PPP1R14B-AS1 were characterized in detail. Functional experiments addressed the impacts of PPP1R14B-AS1 knockdown on breast cancer cells. In this study, PPP1R14B-AS1 was found to be overexpressed in breast cancer, exhibiting a close correlation with poor patient prognosis. Results also showed that breast cancer cell proliferation and motility were suppressed when PPP1R14B-AS1 was silenced. Mechanistically, PPP1R14B-AS1 acted as a competing endogenous RNA for microRNA-134-3p (miR-134-3p) in breast cancer cells. PPP1R14B-AS1 also increased LIM and SH3 protein 1 (LASP1) levels by imitating miR-134-3p in breast cancer cells. Rescue experiments further corroborated that the knockdown of miR-134-3p or an increase in LASP1 restored the aggressive malignant characteristics of breast cancer cells that were weakened by PPP1R14B-AS1 depletion. In summary, PPP1R14B-AS1 facilitated the oncogenicity of breast cancer cells by controlling the miR-134-3p/LASP1 axis. We believe that our findings may contribute to the development of precision therapy techniques in the field of breast cancer treatment.