The 19-year-old has signed a deal that will keep him with the Blades until the summer of 2018, with the option of a further year.
“Che is an emerging talent, he has so much ability,” Blades boss Nigel Adkins said.
“We are excited to have him at our disposal and his form, attitude and application throughout pre-season and into the league season has been fantastic.
“Like all the players, we must manage him correctly and try to improve him.”
