Mineral trioxide aggregate (MTA), as a bioactive material, has a widespread application in clinical practice. To date, the effects of MTA on the proliferation and differentiation of human periodontal ligament stem cells (hPDLSCs) remain unclear. hPDLSCs were isolated from human periodontal ligament tissues and cultured with MTA conditioned media. Cell counting kit‐8 (CCK‐8) assay was performed to assess the proliferation capacity of MTA‐treated hPDLSCs. Immunofluorescence assay, alkaline phosphatase (ALP) activity, alizarin red staining, real‐time RT‐PCR, and western blot analyses were used to investigate the odonto/osteogenic capacity of hPDLSCs as well as the involvement of NF‐κB and MAPK pathways. ALP activity assay revealed that 2 mg/ml was the optimal concentration for the induction of hPDLSCs by MTA. The protein expression of DSP, RUNX2, OCN, OSX, OPN, DMP1, ALP, and COL‐I in MTA‐treated hPDLSCs was significantly higher than those in control group (p < 0.01). When hPDLSCs were treated with the inhibitors of NF‐κB and MAPK pathways (U0126, SP600125, SB203580, and BMS345541), the effects of MTA on the differentiation of hPDLSCs were suppressed. Mechanistically, P65 was detected to transfer from cytoplasm to nuclei, as indicated by western blot and immunofluorescence assay. Moreover, MAPK‐related proteins and its downstream transcription factors were also upregulated in MTA‐treated hPDLSCs. Together, mineral trioxide aggregate can promote the odonto/osteogenic capacity of hPDLSCs via activating the NF‐κB and MAPK pathways. In this study, MTA was used to investigate its influence on the proliferation and differentiation of hPDLSCs. 2 mg/ml MTA promoted the osteo/odontogenic differentiation of hPDLSCs. Furthermore, NF‐κB and MAPK pathways were activated in MTA‐treated hPDLSCs, accompanying with the up‐regulation of downstream transcription factors.