One half chance was the difference between Forest and the Blades in a game of few opportunities.
Lewis Grabban's deft, flicked header from Joao Carvalho's cross found the corner of Dean Henderson's net in the second half.
It took less than two minutes for United to create a chance, following Coutts winning a throw on the right but Norwood's low, powerful drive was wide of Pantilimon's right post. An effort from Coutts was blocked at the edge of the box after Sharp laid off a Stevens cross on ten minutes.
The opening half hour was even, Lolley half-volleyed after a free-kick was partially cleared and Egan was well placed to get United out of trouble on a couple of occasions. Henderson was also off his line quickly to prevent Grabban latching onto a long pass from Carvalho.
Before the break, confirming the half was even, both sides had one more chance each. Egan headed wide from a corner and Forest's Robinson tried his luck with a half-volley from outside the box but Henderson comfortably saved.
Forest's Cash created the first chance of the second half for himself but he faded a shot wide after getting the better of Cranie and Freeman. For United, Stevens fired wide after good work from Clarke, before McGoldrick replaced Coutts.
Freeman blocked brilliantly to deny Cash after an enterprising run from Lolley, whilst a good spell of possession saw Sharp head wide following Norwood's cross.
The decisive goal arrived on 69 minutes and came from the home side. A cross from the right was recycled by Carvalho and his delivery was flicked in by GRABBAN, the ball nestling just inside the far post.
United were unable to put pressure on Pantilimon's goal and boss Wilder made a double change on 80 minutes, plus altered the formation.
The only opportunities, however, came in added time with a free-kick and a couple of corners. From the first, Woodburn had two chances but was unable to find the target and from the second Henderson was added to the attack and launched himself at the ball but he was unable to bring the Blades a late leveller.
Forest: Pantilimon, Figueiredo, Guedioura, Grabban (Ansarifard 90), Carvalho, Cash (Dias 82), Robinson, Dawson, Lolley, Yacob, Darikwa.
Unused: Osborn, Steele, Janko, Tachtsidis, Hefele.
Blades: Henderson, Stevens, Fleck, O'Connell, Clarke, Sharp, Egan, Coutts (McGoldrick 55), Norwood, Freeman (Baldock 80), Cranie (Woodburn 80).
Unused: Stearman, Johnson, Moore, Washington.