In most solid tumors, cellular energy metabolism is primarily dominated by aerobic glycolysis, which fulfills the high demand for biomacromolecules at the expense of reduced ATP production efficiency. Elucidation of the mechanisms by which rapidly proliferating malignant cells acquire sufficient energy in this state of inefficient ATP production from glycolysis could enable the development of metabolism-targeted therapeutic strategies. In this study, we observed a significant association between elevated expression levels of the long noncoding RNA small nuclear RNA host gene 17 (SNHG17) and unfavorable prognosis in breast cancer. SNHG17 promoted breast cancer cell proliferation by augmenting mitochondrial ATP production. Mechanistically, SNHG17 directly interacted with the P65 subunit of NF-κB and phosphorylated P65 at the threonine 505 site. SNHG17 bound to P65 at its truncated loop2 site, recruited P65 to mitochondria, and coregulated the transcriptional activation of mitochondrial DNA to promote ATP production. Accordingly, targeting SNHG17 with an antisense oligonucleotide significantly reduced breast cancer tumor growth both in vitro and in vivo. Overall, these results established a role for SNHG17 in promoting breast cancer progression by increasing ATP production and provided insights into the reprogramming of energy metabolism in solid tumors. Significance: SNHG17 cooperates with NF-κB to induce expression of mitochondrial DNA and boost ATP production in breast cancer, suggesting that targeting SNHG17 could reverse metabolic reprogramming to suppress tumor progression.