The rising fructose intake in sugar-sweetened beverages and ultra-processed foods relates to the high incidence of nonalcoholic fatty liver disease. This study aimed to examine the effects of long-term high-fructose diet intake (for 16 or 20 weeks) on progressive hepatic damage, focusing on the endoplasmic reticulum stress markers and fibrogenesis as possible triggers of liver fibrosis. Forty 3-month-old male C57BL/6J mice were randomly divided into four nutritional groups: C16 (control diet for 16 weeks), C20 (control diet for 20 weeks), HFRU16 (high-fructose diet for 16 weeks), and HFRU20 (high-fructose diet for 20 weeks). Both HFRU groups showed oral glucose intolerance and insulin resistance, but only the HFRU20 group exhibited increased inflammation. The increased lipogenic and endoplasmic reticulum stress markers triggered hepatic fibrogenesis. Hence, time-dependent perivascular fibrosis with positive immunostaining for alpha-smooth muscle actin and reelin in HFRU mice was observed, ensuring fibrosis development in this mouse model. Our study showed time-dependent and progressive damage on hepatic cytoarchitecture, with maximization of hepatic steatosis without overweight in HFRU20 mice. ER stress and liver inflammation could mediate hepatic stellate cell activation and fibrogenesis, emerging as targets to prevent NAFLD progression and fibrosis onset in this dietary model.