Electroactive biofilms formation by the metal-reducing bacterium Geobacter sulfurreducens is a step crucial for bioelectricity generation and bioremediation. The transcriptional regulator GSU1771 controls the expression of essential genes involved in electron transfer and biofilm formation in G . sulfurreducens , with GSU1771-deficient producing thicker and more electroactive biofilms. Here, RNA-seq analyses were conducted to compare the global gene expression patterns of wild-type and Δ gsu1771 mutant biofilms grown on non-conductive (glass) and conductive (graphite electrode) materials. The Δ gsu1771 biofilm grown on the glass surface exhibited 467 differentially expressed (DE) genes (167 upregulated and 300 downregulated) versus the wild-type biofilm. In contrast, the Δ gsu1771 biofilm grown on the graphite electrode exhibited 119 DE genes (79 upregulated and 40 downregulated) versus the wild-type biofilm. Among these DE genes, 67 were also differentially expressed in the Δ gsu1771 biofilm grown on glass (56 with the same regulation and 11 exhibiting counter-regulation). Among the upregulated genes in the Δ gsu1771 biofilms, we identified potential target genes involved in exopolysaccharide synthesis ( gsu1961-63 , gsu1959 , gsu1972-73 , gsu1976-77 ). RT-qPCR analyses were then conducted to confirm the differential expression of a selection of genes of interest. DNA-protein binding assays demonstrated the direct binding of the GSU1771 regulator to the promoter region of pgcA , pulF , relA , and gsu3356 . Furthermore, heme-staining and western blotting revealed an increase in c -type cytochromes including OmcS and OmcZ in Δ gsu1771 biofilms. Collectively, our findings demonstrated that GSU1771 is a global regulator that controls extracellular electron transfer and exopolysaccharide synthesis in G . sulfurreducens , which is crucial for electroconductive biofilm development.