Aims: There has been an increasing trend towards the ulcerative colitis (UC) incidence worldwide. The present study aimed to explore novel biomarkers and potential therapeutic agents for UC. Materials and methods: Differentially expressed genes (DEGs) among UC and healthy control samples were identified by GEO2R online tool. Functional analysis was performed and protein-protein interaction networks were constructed. The hub genes were explored by Cytoscape, and quantitative real-time-PCR (qRT-PCR) was used to valid their expression in clinical samples. ImmuCellAl was utilized to analyze the fraction of 24 types of immune cells. The L1000 platform was applied to determine potential agents for UC treatment. The dextran sulfate sodium (DSS)-induced colitis model was used to identify the therapeutic effect of meclofenamic acid. Key findings: A total of 270 DEGs were identified among UC and healthy control samples. Functional analysis indicated that the DEGs were primarily enriched in several immune response and digestion pathways. A proportion of 18 immune-cell types was found to be significantly altered between UC and healthy control samples. 10 compounds were predicted to have therapeutic potentials for treating UC. Among them, we selected meclofenamic acid to identify its therapeutic effect on UC treatment by animal experiments. Significance: The current study comprehensively analyzed the DEGs and immune infiltration in UC, as well as screened for potential agents for UC treatment.