In this study, we aimed to explore the hepatoprotective effects of the gemmotherapy bud extract ofCorylus avellanain a model of liver fibrosis on diabetic mice. An evaluation of total flavonoids and polyphenols contents and LC/MS analyses were performed. Experimental fibrosis was induced with CCl4(2 mL/kg by i.p. injections twice a week for 7 weeks) in streptozotocin-induced diabetic mice. Our results showed a content of 6–7% flavonoids, while hyperoside and chlorogenic acids were highlighted in the bud extract. Toxic administration of CCl4increased oxidative stress, mRNA expression of the transforming growth factor-β1 (TGF-β1) andSmad 2/3, and reducedSmad 7expression. Furthermore, up-regulation of α-smooth muscle actin (α-SMA) revealed an activation of hepatic stellate cells (HSCs), while collagen I (Col I) up-regulation and matrix metalloproteinases (MMPs) unbalance led to an altered extracellular matrix enriched in collagen, confirmed as well by a trichrome stain and electron microscopy analysis. Treatment with gemmotherapy extract significantly restored the liver architecture and the antioxidant balance, and significantly decreased collagen deposits in the liver and improved the liver function. Our results suggest thatCorylus avellanagemmotherapy extract may have anti-fibrotic effects and could be useful in the prevention and treatment of liver fibrosis. The hepatoprotective mechanism is based on HSC inhibition, a reduction in oxidative stress and liver damage, a downregulation of the TGF-β1/Smad signaling pathway and a MMPs/TIMP rebalance.