The Blades have secured the signature of the striker wanted by Nigel Clough.
United have signed Rochdale's Matt Done for an undisclosed fee. The striker, who has scored 14 goals so far this season, has signed a two-and-a-half year deal with the option for a further year.
The 26-year-old, who lists Barnsley amongst his former clubs, switched to Spotland in the summer of 2013, where he has impressed since being converted into a central striker.
His statistics this season include 10 goals in 23 Sky Bet League One starts, eight assists and two hat-tricks.
Boss Clough was delighted with the late capture: "Matt is a player we have watched extensively over the last few months. We've been impressed with his goals, assists and work-rate. He is lively, can play in a number of attacking positions and he also offers us additional pace in dangerous areas."
Done completed formalities on the deal at United's Shirecliffe training base on Monday evening before telling www.sufc.co.uk: "I'm delighted to sign for a Club the size of Sheffield United. It was just an opportunity I couldn't turn down.
"I'd like to thank everyone at Rochdale, from top to bottom, for the last couple of seasons, I have thoroughly enjoyed my time at Spotland and wish them all the best for the future.
"The aim now is to develop further and I'd love to help to get Sheffield United back to the Championship, where the Club should be. I feel, with the squad and management, this Club is very capable of having a good crack at promotion and personally I'm particularly excited to be playing in front of 20,000 fans every other week."
Done is United's fifth capture of the January transfer window following the signings of Paul Coutts, Kieron Freeman, John Brayford and Jason Holt. Additionally, Jamie Murphy and Terry Kennedy signed extensions on their contracts over the weekend.