Sheffield United scored twice in the final 10 minutes to leave the Royals in the Championship relegation zone.
Reading looked toothless throughout under caretaker boss Scott Marshall, but were nearing a goalless draw at Madejski Stadium before Billy Sharp put the Blades ahead.
And a second goal quickly followed when a corner was turned into his own net by Sam Baldock.
The loss, Royals’ 11th in 20 league games this season, leaves them 22nd in the Championship table.
Marshall made just one change from Paul Clement’s final game in charge last weekend with Josh Sims preferred to John Swift with the late goal saviour against Stoke Mo Barrow again having to settle for a place on the bench. Yakou Meite missed out on the squad altogether.
But the Royals struggled to create anything going forwards in the early stages aside from a wild Chris Gunter effort.
Sheffield United had the ball in the net at the other end after 10 minutes after John Egan flicked a header goalwards. However, the flag was raised by the linesman with Conor Washington offside as he turned in from close range.
The visitors were getting on the front foot and went close when a ball over the top found David McGoldrick, who got in behind Tiago Ilori but clipped his shot into the grateful arms of Anssi Jaakkola.
McGoldrick did find the net just past the half hour mark, flicking in a low George Baldock cross, but again the flag denied him after just straying into an offside position.
The Royals began to find some space on counter attacks but the final product from both wingers Garath McCleary and Sims was poor as goalkeeper Dean Henderson remained untested during a goalless first half.
Sheffield United came flying out of the traps after the restart with Jaakkola called into a smart stop to turn McGoldrick’s effort behind. The resulting corner also went close with Chris Basham getting a header on target, but Gunter got back to head off the line.
Gunter was called into another last-ditch defensive headed clearance, as was Blackett as the Blades began to deliver more crosses from the wings but the Royals held firm.
Marshall turned to his bench midway through the half, introducing both Barrow and Sam Baldock for the disappointing Sims and Marc McNulty but it was Sheffield United who were looking the more likely scorers.
McGoldrick saw a header comfortably saved by Jaakkola before substitute Sharp missed a glorious chance, heading wide in acres of space in the penalty area.
However, Sharp would have the last laugh, ghosting in to score from inside the six-yard box after Basham’s deflected cross fell kindly into his path at the back post.
And things went from bad to worse minutes later when John Fleck’s corner was turned in by a combination of Jack O’Connell and Sam Baldock to kill the game and give the visitors all three points.
READING: Jaakkola; Yiadom, Ilori, Blackett, Gunter; Rinomhota, Bacuna (c); Sims (Barrow 64), Loader, McCleary (Aluko 85); McNulty (S. Baldock 64).
Subs not used: Mannone, McIntyre, Kelly, Swift.
Yellow card: Loader (80)
SHEFF UTD: Henderson; G. Baldock, Basham, Egan, O’Connell, Stevens; Norwood (c), Lundstram (Duffy 45), Fleck; McGoldrick, Washington (Sharp 60).
Subs not used: Moore, Cranie, Stearman, Coutts, Johnson.
Goals: Sharp (83), S. Baldock (OG) (86)
Yellow card: Fleck (23)
Referee: James Linington
Attendance: 12,066 (inc. 1,066)