The objective of this study was to assess the role of UbK, a novel protein kinase, in the growth of Bacillus subtilis, especially under oxidative stress conditions. Growth profiles of wild-type and ΔubK mutant strains were assessed in the presence of paraquat, an in vivo inducer of oxidative stress. Wild-type B. subtilis cells were able to efficiently survive the stress conditions, whereas the growth profile of the ΔubK mutant strain was significantly affected. Complementation of the ΔubK mutant with a plasmid coding for a wild-type UbK restored wild-type growth phenotypes. Furthermore, we used recombinant plasmids containing the genes of the active kinase (UbK) and its inactive form (E106AUbK) to transform wild-type and ΔubK mutant strains. Our results showed that an active form of UbK is needed to restore a normal growth profile. Protein kinases allow a fine-tuning of cellular processes, including those related to metabolic adaptation to environmental cues. Our findings highlight the importance of an active UbK in the bacterial growth under oxidative stress in B. subtilis. This study revealed the role of a new protein kinase, UbK, allowing B. subtilis to survive oxidative stress.