Transcription factors (TFs) regulate gene expression by binding to DNA. The NAC gene family in plants consists of crucial TFs that influence plant development and stress responses. The whole genome of <i>Capsicum annuum</i> shows over 100 NAC genes (<i>CaNAC</i>). Functional characteristics of the most CaNAC TFs are unknown. In this study, we identified <i>CaNAC4</i>, a novel NAC TF in <i>C. annuum</i>. <i>CaNAC4</i> expression increased after inoculation with the pathogens, <i>Xanthomonas axonopodis</i> pv. <i>vesicatoria</i> race 3 and <i>X. axonopodis</i> pv. <i>glycines</i> 8ra, and following treatment with the plant hormones, salicylic acid and abscisic acid. We investigated the functional characteristics of the <i>CaNAC4</i> gene and its roles in salt tolerance and anti-pathogen defense in transgenic <i>Nicotiana benthamiana</i>. For salt stress analysis, the leaf discs of wild-type and <i>CaNAC4</i>-transgenic <i>N. benthamiana</i> plants were exposed to different concentrations of sodium chloride. Chlorophyll loss was more severe in salt stress-treated wild-type plants than in <i>CaNAC4</i>-transgenic plants. To analyze the role of <i>CaNAC4</i> in anti-pathogen defense, a spore suspension of <i>Botrytis cinerea</i> was used to infect the leaves. The disease caused by <i>B. cinerea</i> gradually increased in severity, and the symptoms were clearer in the <i>CaNAC4</i>-transgenic lines. We also investigated hypersensitive response (HR) in <i>CaNAC4</i>-transgenic plants. The results showed a stronger HR in wild-type plants after infiltration with the apoptosis regulator, <i>BAX</i>. In conclusion, our results suggest that <i>CaNAC4</i> may enhance salt tolerance and act as a negative regulator of biotic stress in plants.