Background: At the therapeutic doses, diclofenac sodium (DFS) has few toxic side effects on mammals. On the other hand, DFS exhibits potent toxicity against birds and the mechanisms remain ambiguous. Objectives: This paper was designed to probe the toxicity of DFS exposure on the hepatic proteome of broiler chickens. Methods: Twenty 30-day-old broiler chickens were randomized evenly into two groups (n = 10).DFS was administered orally at 10 mg/kg body weight in group A, while the chickens in group B were perfused with saline as a control. Histopathological observations, serum biochemical examinations, and quantitative real-time polymerase chain reaction were performed to assess the liver injury induced by DFS. Proteomics analysis of the liver samples was conducted using isobaric tags for relative and absolute quantification (iTRAQ) technology. Results: Ultimately, 201 differentially expressed proteins (DEPs) were obtained, of which 47 were up regulated, and 154 were down regulated. The Gene Ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analysis were conducted to screen target DEPs associated with DFS hepatotoxicity. The regulatory relationships between DEPs and signaling pathways were embodied via a protein-protein interaction network. The results showed that the DEPs enriched in multiple pathways, which might be related to the hepatotoxicity of DFS, were “protein processing in endoplasmic reticulum,” “retinol metabolism,” and “glycine, serine, and threonine metabolism.” Conclusions The hepatotoxicity of DFS on broiler chickens might be achieved by inducing the apoptosis of hepatocytes and affecting the metabolism of retinol and purine. The present study could provide molecular insights into the hepatotoxicity of DFS on broiler chickens.