The liver is a vital organ in chickens that performs a number of crucial physiological functions, including the storage of hepatic glycogen, protein synthesis, detoxification, and deoxidation.  The growth and metabolism of the liver are complex processes influenced by factors such as environment, diet, and genetics.  MicroRNAs (miRNAs), as post-transcriptional regulatory molecules, play a role in various biological processes.  There is growing evidence that miR-27b-5p plays a key role in the regulation of liver development and metabolism in various species.  However, its role in chicken livers has yet to be determined.  In our experiment, we found that chickens with fatty livers had significantly higher levels of serum triglyceride (TG) and total cholesterol (TC) compared to the normal chickens, while the control group had significantly higher levels of very low-density lipoprotein (VLDL) and serum hormones.  Further research showed that the mRNA of miR-27b-5p was highly expressed in fatty livers.  By exploring the function of miR-27b-5p in chicken livers, we discovered that it promotes lipogenesis, oxidative stress, and inflammatory responses, leading to hepatocyte apoptosis.  Our study also established the mechanism by which miR-27b-5p interacts with its target gene, and found that miR-27b-5p targets insulin receptor substrate 2 (IRS2) and modulates the PI3K/AKT signaling pathway.  Additionally, our investigation of IRS2 in chicken hepatocytes revealed that knocking down IRS2 has the same effects as overexpressing miR-27b-5p.  In conclusion, our study revealed that miR-27b-5p directly binds to IRS2, inhibiting the PI3K/AKT signaling pathway and causing steatosis, oxidative stress, inflammation, and apoptosis in chicken liver.