Proliferating cell nuclear antigen binding factor (encoded by KIAA0101/ PCLAF) regulates DNA synthesis and cell cycle progression; however, whether the level of KIAA0101 mRNA in lung adenocarcinoma is related to prognosis and tumor immune infiltration is unknown. In patients with lung adenocarcinoma, the differential expression of KIAA0101 was analyzed using the Oncomine, GEPIA, and Ualcan databases. The prognosis of patients with different KIAA0101 expression levels was evaluated using databases such as Prognostan and GEPIA. Tumor immune infiltration associated with KIAA0101 was analyzed using TISIDB. Linkedmics was used to perform gene set enrichment analysis of KIAA0101. KIAA0101 expression in lung adenocarcinoma tissues was higher than that in normal lung tissues. Patients with lung adenocarcinoma with low KIAA0101 expression had a better prognosis than those with high KIAA0101 expression. We constructed the gene regulatory network of KIAA0101 in lung adenocarcinoma. KIAA0101 appeared to play an important role in the regulation of tumor immune infiltration and targeted therapy in lung adenocarcinoma. Thus, KIAA0101 mRNA levels correlated with the diagnosis, prognosis, immune infiltration, and targeted therapy in lung adenocarcinoma. These results provide new directions to develop diagnostic criteria, prognostic evaluation, immunotherapy, and targeted therapy for lung adenocarcinoma.