Mj olnir is a novel deep learning-based global lightning flash density parameterization framework. Trained using ERA5 atmospheric predictors and WWLLN observations, it captures the nonlinear mapping between large-scale environmental conditions and lightning activity. Based on the InceptionNeXt backbone and SENet, it employs a multi-task learning strategy to simultaneously predict lightning occurrence and intensity. It accurately reproduces the distribution, seasonal variability, and regional characteristics of global lightning activity, achieving a global Pearson correlation coefficient of 0.96 for the annual mean field. This suggests that Mj olnir is not only an effective data-driven global lightning parameterization but also a promising AI-based approach for next-generation Earth System Models (AI-ESMs).