• Cr doping in FeCoNiSiB MPEAAs lowers glass-transition and crystallization temperatures, with optimal soft magnetic properties at 3 at.% Cr (saturation ~0.578 T, coercivity ~5.5 A/m).
• Increasing Cr content enhances corrosion resistance, with 8 at.% Cr exhibiting the highest pitting potential (0.288 V) and widest passive region (0.628 V) in 3.5 wt.% NaCl solution.
• Microhardness decreases with Cr addition but remains above 810 HV0.5, indicating good mechanical integrity.
• The study provides insights into designing multi-principal element amorphous alloys with tailored magnetic and anti-corrosion performance for advanced engineering applications.