This study was carried out to explore the role of the long noncoding RNA (lncRNA) SAMMSON in triple-negative breast cancer (TNBC). The research patients in this study included 68 TNBC patients. Cell Counting Kitcck-8 were utilized to determine cell proliferation abilities, respectively. Proteins and mRNAs were estimated by western blot and Methylation-specific polymerase chain reaction, respectively. We found that SAMMSON was upregulated, while p53 was downregulated in cancer (TNBC) tissues than in non-cancer tissues of TNBC patients. SAMMSON expression levels in TNBC tissues increased with the increase of clinical stages of TNBC patients. SAMMSON and p53 were inversely correlated in TNBC tissues. In TNBC cells, SAMMSON overexpression decreased p53 expression, while p53 overexpression failed to affect SAMMSON expression. In addition, SAMMSON overexpression increased TNBC cell proliferation, while p53 overexpression decreased the proliferation rates of TNBC cells. In addition, p53 overexpression attenuated the effects of SAMMSON overexpression. Therefore, overexpression of SAMMSON could promote TNBC cell proliferation by interacting with p53.