BRCA1/BRCA2-containing complex subunit 3 (BRCC3) has been proved to exert pro-inflammatory effect in various inflammatory diseases through different mechanisms, but its involvement in pulpitis remains unclear. This study aims to investigate the regulatory role and mechanisms of BRCC3 in modulating dental pulp cell inflammation and pulpitis progression. The expression of BRCC3 was observed to be elevated in human/mouse pulpitis samples and lipopolysaccharide-stimulated human dental pulp cells (hDPCs). Manipulation of BRCC3 expression revealed that BRCC3 facilitated the expression of pro-inflammatory cytokines and apoptosis of hDPCs. RNA-sequencing and gene set enrichment analysis were utilized to explore the downstream signaling pathways related to BRCC3 functions. Dual luciferase reporter assay, western blot, and immunofluorescence staining were conducted for further validation. The results demonstrated that BRCC3 expedited IκBα phosphorylation and degradation, as well as p65 phosphorylation and nuclear translocation in hDPCs, ultimately activating the nuclear factor kappa B (NF-κB) signaling pathway. Moreover, conditional knockout of Brcc3 in mouse dental pulp cells effectively impeded the expression of IL-6, recruitment of immune cells, and necrosis of inflamed pulp tissue after 1 day and 1 week of pulp exposure. The level of p-p65 in Brcc3 conditional knockout mice was lower than the control mice, indicating the inhibition of NF-κB. Taken together, BRCC3 promotes pulpitis by activating the NF-κB signaling pathway in dental pulp cells.