The conserved Blm10/PA200 family belongs to the proteasome activators. PA200 alternatively binds to the proteasome core particle (CP) and facilitates peptide degradation in an ATP and ubiquitin-independent manner. PA200 has several important physiological roles, such as DNA repair, spermatogenesis, and aging. However, the exact molecular mechanisms behind these functions are not clear. In the present study, we investigated new promising functions of PA200 and the consequences of PA200 stable depletion at the normal condition and upon mitochondrial stress. First, we investigated the role of PA200 on cell viability and apoptosis with or without mitochondrial stress. We have found that PA200 deficient cells are more sensitive to rotenone but not oligomycin and antimycin A treatment. Furthermore, PA200-deficient cells exhibit low expression of c-Jun upon rotenone treatment, thereby; reducing the capacity of PA200 depleted cells to tolerate the rotenone-induced cell death. Second, we performed ChIP followed by ChIP-sequencing analysis to study the possible role of PA200 as a transcription factor or cofactor that regulates the transcription machinery. We have demonstrated that PA200 is a chromatin component in SH‐SY5Y neuroblastoma cells and it binds to promoter regions of genes involved in the cell cycle, metabolism, and protein modification. Third, we performed an RNA sequencing study. We found that the loss of PA200 has an overall change in the transcriptomic profile of the SH-SY5Y cell line. Functional annotation analysis of differentially expressed genes (DEGs) revealed that PA200 has a crucial role in cellular functions including apoptosis, metabolism, cell cycle, MAPK signaling pathway, and mitochondrial homeostasis. Furthermore, the extracellular flux analysis of shPA200 and control cells indicates mitochondrial dysfunction and a significant increase in glycolysis in PA200 deficient cells. Further investigations of mitochondrial mass show a significant reduction in mitochondrial ETC biogenesis upon loss of PA200. Finally, mitochondrial morphology analysis shows significant increase in fused mitochondria in shPA200 cells, compared to control cells upon oligomycin treatment due to maintenance of L-OPA1 isoforms. Our new findings provide more information regarding the role of PA200 in eukaryotic cells. The new disclosed functions of PA200 in the maintenance of mitochondrial integrity and cell survival may contribute to the development of new therapy for many diseases related to mitochondrial dysfunction including but not limited to neurodegenerative disease, cardiovascular disease, and aging.