John Fleck has today signed a new four-year deal with the Blades, that sees him contracted to the club until the end of 2020/21 campaign.
Signed on a free transfer from Coventry City in the summer of 2016, the 26-year-old played an instrumental part in helping United romp to the League One title last term, making 49 appearances in all competitions, scoring four times.
And this season, the former Scotland U21 international has impressed back in the second tier, starting all of the Blades eight league matches to date.
Speaking having put pen-to-paper, Fleck commented: "I'm delighted to get my new contract sorted and it's all happened easily and pretty quickly. The Gaffer spoke to me last week and it's happened from there really. I've settled well here and it was an easy decision to make. Obviously, I'm very happy."
On the news, boss Chris Wilder added: "John came in on a free transfer and was a major part of our success last season. He has settled back into the Championship and we're delighted that he sees his long-term future here with us.
"I've said previously that John is one that can grow as the club grows and we're delighted with the partnership he has struck up with Paul Coutts in the middle of the park.
"John is at a fantastic age at 26 and by getting him tied down we should have him during the best years of his career."