Welcome to the Blades, Ethan. ✍️ pic.twitter.com/quuGheS07W— Sheffield United (@SheffieldUnited) September 7, 2020
"He brings a lot of qualities to the group and he's someone we've tracked for two or three seasons."
Ampadu made one Premier League appearance for Chelsea, in 2017/18, before going out on loan to RB Leipzig last season. He has made 15 appearances for Wales.
Sheff Utd open their 2020/21 Premier League season at home to Wolverhampton Wanderers on Monday.