Objective To identify the expression profiles of mRNA and circular RNA (circRNA) in pericardial interstitial cells (PICs) that overexpress Krüppel-like factor 4 (KLF4) through microarray analysis, and to explore the potential regulatory mechanism of KLF4 in pericardial fibrosis. Methods PICs were infected with adenovirus carrying KLF4 (Ad.KLF4) or enhanced green fluorescent protein gene (Ad.EGFP). Microarray analysis was used to identify differentially expressed mRNAs and circRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze gene functions and signaling-pathway enrichment. The effects of KLF4 on PIC proliferation and phenotypic transformation were evaluated by cell counting kit 8 (CCK-8) and Western blotting, and a circRNA-miRNA-mRNA regulatory network was constructed. Results Compared with PICs infected with Ad.EGFP, significantly differentially expressed mRNA (n＝6 197) and circRNA (n＝393) were identified in PICs infected with Ad.KLF4. GO analysis showed that the differentially expressed genes were significantly enriched in biological processes related to cell proliferation and differentiation. KEGG pathway enrichment analysis showed that the differentially expressed mRNAs were associated with the PI3K/Akt signaling pathway. Western blotting and CCK-8 assays confirmed that KLF4 could inhibit TGF-β1-induced cell proliferation and phenotypic transition, and this effect might be achieved through the PI3K/Akt signaling pathway. Bioinformatics analysis revealed that the circRNA host genes enriched in the PI3K/Akt pathway included lysophosphatidic acid receptor 3 (LPAR3), thrombospondin 1 (THBS1), and protein phosphatase 2 catalytic subunit α (PPP2CA); and based on this, a KLF4-regulated PI3K/Akt pathway-related circRNA-miRNA-mRNA network was constructed. Conclusion KLF4 may inhibit the proliferation and phenotypic transition of PICs by regulating the circRNA-miRNA-mRNA network related to the PI3K/Akt signaling pathway, providing a new target for anti-fibrotic therapy.