Telomeric-repeat containing RNA (TERRA) is a long non-coding RNA transcribed from the telomeric region, and our preliminary data indicated that TERRA plays a crucial role in cellular senescence. Numerous studies have shown TERRA’s effect on cellular senescence, but more time and research are required to fully understand the mechanics of TERRA. In past research, it has been shown that the TERRA level has increased in senescence cells; therefore, in this research, we study the effect of TERRA in cellular senescence by transfecting TERRA RNA and TERRA RNA:DNA hybrid into the human primary fibroblast, BJ cell line, to simulate an aging cell environment. From the result, the expression of type I interferon (IFN-α and IFN-β) and type III interferon (IFN-λ1) increased after both RNA and RNA:DNA hybrid transfection. Combined with our previous finding, these results indicate that the immune response activation during senescence is driven by TERRA upregulation without a strand-specificity effect. Together, we tested the expression levels of cytosolic sensors (cGAS, MDA5, RIG-I) and all of their expression level elevated, revealing that TERRA could activate the immune response via cGAS/STING signaling and mitochondria anti-virus signaling (MAVS). We also found that the expression level of endogenous TERRA (1q, 3q, 8p, 15q) is not affected by exogenous TERRA delivery. We investigated the expression level change in mitochondrial biogenesis genes (PGC-1α, NRF1, NRF2, and TFAM) and our data showed that the expressions of PGC-1α, NRF2, and TFAM genes are decreased after TERRA expression. Similarly, the expression level of antioxidant genes (NFE2L1, NFE2L2) are also decreased in TERRA transfected group compared to the control. Together, these results indicate that expression of TERRA regulates mitochondria biogenesis and antioxidant genes expression in human primary fibroblast. Finally, we performed immunofluorescence staining to test localization of TERRA in the cell. We discovered that TERRA forms the aggregated form and localizes to mitochondria, which also change the mitochondria morphology. These findings indicate that TERRA has a crucial contribution on cellular senescence, especially in regulation of immune response and mitochondria activity.