Acute liver failure (ALF) occurs due to severe liver damage that triggers rapid loss of normal liver function. Here, we investigate the usefulness of an injectable liver extracellular matrix (LECM)–rich hydrogel generated from an optimized decellularization protocol incorporated with silver nanoparticles (AgNPs) as a promising therapy for ALF. First, we optimized a non‐destructive protocol for rat liver decellularization to obtain ECM‐rich well‐preserved scaffold. Then, LECM hydrogel generated from two commonly used decellularization protocols were compared by LECM hydrogel obtained from our optimized protocol. The ALF model was induced by an intraperitoneal (IP) thioacetamide (TAA) injection followed by the IP injection of LECM hydrogel, collagen‐AgNPs mixture or LECM hydrogel‐AgNPs mixture. LECM‐rich scaffold and hydrogel were successfully obtained using our optimized decellularization protocol. Use of the LECM hydrogel‐AgNPs mixture to treat TAA induced ALF, greatly improving liver injury and histological liver regeneration. Interleukin‐6 (IL‐6) and transforming growth factor beta ( TGF‐β) expressions were significantly reduced, while albumin, hepatocyte growth factor, and Ki67‐positive cells were highly expressed. Moreover, aspartate transaminase (AST) and alanine transaminase (ALT) plasma levels, and liver homogenate nitric oxide (NO) level were significantly lowered. In conclusion, the LECM hydrogel‐AgNPs mixture has potential efficient therapeutic and regenerative effects on TAA‐induced liver injury. This article is protected by copyright. All rights reserved.