Birmingham moved up to eighth place in the First Division and in the process carved out one of their best victories of the season, with goals from Martin Grainger and Johnson in the 31st and 66th minutes.
Sheffield United's determination to attack proved to be their downfall on this occasion as Birmingham produced one of their best performances of the season. The visitors were caught when, in the 31st minute, Lee Sandford's corner was plucked out of the air by Ian Bennett. The Birmingham goalkeeper spotted the unmarked Jon McCarthy. He quickly slipped a 30- yard forward pass through to Grainger, who slid the ball past Alan Kelly.
The visitors were unable to come back and were often indebted to Kelly for keeping them in the game as he demonstrated when he kept out a 30- yard drive from Simon Charlton.
Birmingham's attacking supremacy sealed the game with Johnson's goal when the unmarked defender was able to convert a Martin O'Connor cross from inside the six-yard box.
The Birmingham manager, Trevor Francis, paid tribute to Johnson's contribution. He said: "Michael Johnson has made a big improvement during my time at the club and he's a vital member of the squad.
"After his first ever goal for the club I gave him the match ball and a bottle of champagne. If he continues to play like he did against Sheffield United, he will be picking up a lot more presents."
He added: "I was very pleased with the way we achieved our win. To play like this against a side like Sheffield United and prevent them from making a single attempt on goal speaks volumes for the side."
His United counterpart, Nigel Spackman, was critical of his team. "There were too many players in my side who under-performed," he said.
Goals: Grainger (31) 1-0; Johnson (66) 2-0.
Birmingham City: Bennett; Bass, Charlton, Bruce, Johnson (Purse, 90), Grainger, McCarthy, O'Connor, Adebola, Hughes (Robinson 88), Ndlovu (Forster, 89).
Sheffield United: Kelly; Borbokis (Derry, 46), Quinn (Kachuro, 69), Barrett, Sandford, Holdsworth, Saunders, Marker, Taylor (Marcello, 69), Ford, Stuart.
Referee: B Knight (Orpington).
Man of the match: Johnson.Reuse content