Aim To identify whether Kruppel-like factor 5 (KLF5) was involved in odontoblastic differentiation during reparative dentine formation. Methodology Human Dental pulp cells (DPCs) were isolated from healthy human dental pulp tissue and induced for odontoblastic differentiation. Alizarin Red staining, alkaline phosphatase (ALPase) activity, quantitative real-time PCR and Western Blot were performed to evaluate in vitro odontoblastic differentiation. The expression profile of KLF5 during the in vitro odontoblastic differentiation was determined by quantitative real-time PCR and Western Blot. Knock-down of KLF5 by lentivirus-mediated shRNA was performed to determine the function of KLF5 in odontoblastic differentiation. After direct pulp capping with MTA, the maxillary first molar segments dissected from male Wistar rats were prepared for histology analysis and immunohistochemistry staining. Results Odontoblastic differentiation was confirmed by significantly increased alkaline phosphatase (ALP; P = 0.004) activity and upregulated odontoblastic differentiation-related genes including dentine sialophosphoprotein (DSPP; P = 0.004) and dentine matrix protein-1 (DMP-1; P = < 0.001). The expression of KLF5 was significantly upregulated during odontoblastic differentiation of in vitro cultured DPCs (P = 0.0002). KLF5 knock-down impaired odontoblastic differentiation. After direct pulp capping, dentine bridge-like calcified tissues were formed under the perforation sites. KLF5 was expressed in odontoblast-like cells and DPCs beneath the perforation sites during reparative dentine formation. Conclusions KLF5 might be involved in the process of odontoblastic differentiation during reparative dentine formation.