Abstract: To enhance the microbiologically influenced corrosion (MIC) resistance of FeCoNiCrMn high entropy alloy (HEAs), a series of Fe_xCu_(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs were prepared. Microstructural characteristics, corrosion behavior (morphology observation and electrochemical properties), and antimicrobial performance of Fe_xCu_(1−x)CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa. The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties. Results revealed that all Fe_xCu_(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs exhibited an FCC (face centered cubic) phase, with significant grain refinement observed in Fe_0.75Cu_0.25CoNiCrMn HEA. Electrochemical tests indicated that Fe_0.75Cu_0.25CoNiCrMn HEA demonstrated lower corrosion current density (i_corr) and pitting potential (E_pit) compared to other Fe_xCu_(1−x)CoNiCrMn HEAs in P. aeruginosa-inoculated medium, exhibiting superior resistance to MIC. Anti-microbial tests showed that after 14 d of immersion, Fe_0.75Cu_0.25CoNiCrMn achieved an antibacterial rate of 89.5%, effectively inhibiting the adhesion and biofilm formation of P. aeruginosa, thereby achieving resistance to MIC.