The development of robust biocatalysts producing a large range of organic amides by hydration of nitriles is an important pursuit and challenge. A nitrilase with a broad range of nitrile substrates was switched to a nitrile hydratase by rationally regulating the reaction pathways. Five mutants improved the amide formation in the product, and four of them formed >50% amide. F193N, with the highest amide formation among the four mutants, improved its amide product up to 73%, which was 35-fold that of the wild type, while maintaining 50% activity relative to the wild type. This study would afford a new synthetic route to amides from nitriles and could be a valuable addition to the synthetic repertoire. Further protein engineering may expand the reaction range of an enzyme to afford more additional pathways to synthetic biology.