Abstract: Because of the potential carcinogenic effects and difficult degradation of azo dyes, their degradation has been a longstanding problem. The degradation of azo dye Direct Blue 6 (DB6) using ball-milled (BM) high-entropy alloy (HEA) powders was characterized in this work. Newly designed AlFeMnTiM (M=Cr, Co, Ni) HEAs synthesized by mechanical alloying (MA) showed excellent performance in the degradation of azo dye DB6. The degradation efficiency of AlFeMnTiCr is approximately 19 times greater than that of the widely used commercial Fe-Si-B amorphous alloy ribbons and more than 100 times greater than that of the widely used commercial zero-valent iron (ZVI) powders. The galvanic-cell effect and the unique crystal structure are responsible for the good degradation performance of the BM HEAs. This study indicates that BM HEAs are attractive, valuable, and promising environmental catalysts for wastewater contaminated by azo dyes.