To analyze the association between difficulties in emotion regulation and problematic pornography use (PPU) and test the mediating effect of loneliness. All 339 participants (M = 28.53 years, SD = 10.32) completed online self-report scales assessing difficulties in emotion regulation, PPU, and loneliness. Difficulties in emotion regulation are positively correlated with PPU. Loneliness partially mediates the relationship between difficulties in emotion regulation and PPU. Gender and intimate relationship status had moderating effects on the tested mediation model. Greater difficulties in emotion regulation have a significant indirect effect on PPU through loneliness.