In line with an important role of autophagy in the development of fibrosis and NASH, we report herein that hepatocyte‐specific ASK1‐knockout mice develop liver fibrosis as evidenced by high collagen deposition, elevated protein levels of α‐SMA, and increased expression of Col1a1. Fibrosis formation was paralleled by elevated expression of inflammatory cytokines such as Il‐6 and Tgfβ1. Thus, ASK1 suppresses the formation of NASH and fibrosis formation, potentially via activation of autophagy. Here, COL1A1 is linked to metabolic dysfunction-associated steatohepatitis.