The 22-year-old, who had five loan spells at different clubs before making his senior Blades debut earlier this season, agreed a permanent switch to Hull on Friday after the terms of the agreement were finalised.
After taking a loan from the English Football League last season, City are currently not allowed to pay fees for any signings – a difficulty they will again encounter when they look to bring United’s Regan Slater back to East Yorkshire before Tuesday night’s 11pm transfer deadline.
As such, Smith made the switch to Hull on a free transfer – although Hull Live report that United will receive a fee from Hull if Smith is sold on in the future.
United confirmed on Friday that Smith had left “for an undisclosed fee” after “seeking first-team football”. He made his City debut at the weekend, in a goalless draw at home to AFC Bournemouth.
“It’s nice to earn a permanent move,” Sheffied-born Smith admitted.
“I’ve been up and down the country to different clubs on loan since I was 18 and, while it has been great to get first team experience, you just want to settle and make somewhere your home.
“I feel Hull City is the perfect club for me in that respect.”