The Blades were the dominant side from start to finish and carved out numerous chances to find a goal.
But despite the pace of Danny Cadamarteri and the industrious probing of Jon Harley they could not find a way through.
And indeed Gillingham could have snatched the most unlikely of winners with 15 minutes left when, with their only chance of the game, Mamady Sidibe glanced a six-yard header wide.
United boss Neil Warnock opted to change his formation for the clash, abandoning his three-pronged strike force which failed to fire in the 5-1 defeat against Ipswich in midweek.
Andy Gray dropped to the bench and was replaced by defender Derek Geary but the Blades were still without Michael Tonge (ankle) and Alan Wright (stomach).
Meanwhile, Gillingham kept faith with Darius Henderson and Sidibe in attack while Tommy Johnson was on the bench.
The visitors saw little of the ball early on as they were pinned on the back foot - with Harley pulling all the strings for United.
It took just a minute for the hosts to stamp their authority on the game as Cadamarteri saw an 18-yard snapshot hacked away by Chris Hope before Harley fired in the first of three quickfire efforts from the resulting corner.
The combative playmaker drilled powerfully at goal after the ball had broken to him on the edge of the area, but goalkeeper Jason Brown was equal to the test.
Soon after Harley threatened again with a curling effort from the left channel.
And with 15 minutes gone Danny Spiller threw himself in the way to block another goalbound shot as Harley again piled forward.
Five minutes later Paul Thirlwell became the first player to be booked following a clumsy challenge on Andrew Crofts before Cadamarteri sent another effort straight at Brown from 25 yards.
For their part, Gillingham were woefully short of attacking ideas and despite their tireless running, Henderson and Sidibe were denied the service to cause any problems for the home defence.
Andy Hessenthaler sent on Paul Smith for Matthew Jarvis in a bid to inject some creativity at the break and for a while at least the Gills looked a much more dangerous side.
But normal service was soon resumed and on the hour mark Andy Liddell fired in a dangerous cross that forced Brown to parry the ball away.
Despite once again dominating possession, United were finding it more difficult to carve out chances in the second half and it was 66 minutes before Cadamarteri skewed a weak effort straight into Brown's hands.
But Harley then missed a gilt-edged opportunity to win it six minutes later when he thumped a powerful six-yard header over the crossbar.
With time running out Gillingham finally created their first chance of the game - and it was almost enough to hand them the points.
After picking up the ball out wide Hessenthaler raced to the by-line before arcing in a cross, but with the goal at his mercy Sidibe could only glance wide.
And with United piling forward they almost snatched a winner themselves in injury time but Chris Morgan's right-footed volley flew over.