Under global warming, the change of lightning activity is a controversial issue. This study investigates historical trends in lightning over the Tibetan Plateau (TP) based on 18-years lightning data detected by optical transient detector (OTD) and lightning imaging sensor (LIS). Local and remote meteorological factors from reanalysis datasets are used to analyze the primary parameters controlling the change of lightning activity. To explore the proxy of lightning flash density over the TP, we employed multiple linear regression through k-fold cross validation. Furthermore, future projections of lightning activity are examined based on outputs of climate models from Coupled Model Intercomparison Project 6 (CMIP6). Historical analysis reveals that flash density over the eastern TP has shown consistently positive trends with a significant increase at a rate of 0.064 fl km− 2 y− 2 over the entire observation period. Our ensemble model mean indicates that sea surface temperature of northwest of Australia and local surface temperature are closely related to the interannual variations in lightning activity over the eastern TP, accounting for 67 % of the variation in flash density. By applying the developed regional proxy to climate models, our projections suggest that lightning activity will increase by 32 % under SSP1–2.6 scenario and by 60 % under SSP2–4.5 scenario by the end of this century.