Jasper Johns, who joined the Blades last week, is looking forward to reuniting his relationship with David Weir.
The 18-year-old, who is equally comfortable at left-back or on the left of a midfielder four, is delighted to have secured his future ahead of the new campaign.
Johns added: "It is a good club for me so quickly having left Everton. Hopefully I can play a part in the forthcoming season. I played really well against United's youth team last season and we kept in touch from that day to be honest.
"I was obviously disappointed to be released but these things happen in football and this move proves things can develop quickly.
"I had no hesitation coming here because this is a big club with ambition to play a lot higher than League One."
On working with Weir, Johns added: "David (Weir) is a fantastic coach and very relaxed. I trained a lot with him at Goodison Park and his training methods help gets the best out of you.
"I hope to prove to him I deserve a first-team spot as the season progresses, I am versatile and quick, they are big features of my game."