The last time the Blades Played Boro,Rob Hulse gave the Blades the lead but that was ruled out by a Yakubu strike on 49 minutes.
But Phil Jagielka scored in the 90th minute to lift the Blades off the bottom of the table.
It seemed the match was destined to end in a draw until captain Jagielka's injury-time winner gave the Blades their first Premiership win since beating Newcastle in April 1994 and lifted them off the foot of the table.
Here were the teams:
Sheffield United: Kenny, Bromby, Jagielka, Davis, Armstrong, Gillespie, Leigertwood, Tonge, Quinn, Kazim-richards, Hulse.
Middlesbrough: Schwarzer, Davies, Woodgate, Pogatetz, Taylor, Morrinson, Cattermole, Rochemback, Downing, Viduka, Yakubu.