OBJECTIVE The study aimed to investigate the role of miR-146a-5p in osteogenesis of hPDLSCs irradiated with low-energy red LEDs. METHODS After irradiation with 5 J/cm2 red LED, miR-146a-5p expression was detected by real-time quantitative polymerase chain reaction (RT-qPCR), and osteogenic markers expression was determined by RT-qPCR and Western blotting. Alkaline phosphatase (ALP) activity was assessed by ALP staining, and mineralization was assessed by Alizarin Red staining, respectively. Lentiviral vectors were designed to regulate miR-146a-5p expression. Dual-luciferase reporter assay was performed to confirm the targeted relationship between miR-146a-5p and MAPK1. Short hairpin RNA (shRNA) was used to regulate MAPK1 expression. RESULTS RT-qPCR and western blotting revealed that 5 J/cm2 irradiation elevated the levels of the osteogenic markers osterix (OSX) and bone sialoprotein (BSP) in hPDLSCs. miR-146a-5p is downregulated in hPDLSCs under the low-energy red LED light irradiation. miR-146a-5p underexpression markedly promoted the osteogenic potential of hPDLSCs. miR-146a-5p targeted MAPK1. 5 J/cm2 red LED irradiation rescued the inhibitory effects of upregulated miR-146a-5p on osteogenic differentiation, and the positive influence of red LED irradiation could be reversed by downregulated MAPK1. CONCLUSIONS These findings confirm that miR-146a-5p is involved in the effect of LED irradiation on the osteogenic differentiation of hPDLSCs by targeting MAPK1. Red LED irradiation may be a potential clinical adjunct therapy for periodontal regeneration.