Mick McCarthy's improving Sunderland side were good value for their third away victory, hitting the home side on the break in the first period and slowly taking control in the second, despite the dismissal of the impressive Argentinian Julio Arca for two yellow card offences.
Sunderland striker Marcus Stewart also turned in an eye-catching display and it was his fine cross on 68 minutes that the diving Kyle headed home for the match-winner.
Following a whirlwind opening period there was no respite after the restart, with Phil Jagielka testing Sunderland keeper Mart Poom from distance.
But not for the first time Sunderland's Arca reminded the home faithful of his potent left-foot, drilling another goalbound 30-yarder which Jagielka did well to block.
Stewart saw his shot from the edge of the area cleared off the line by Chris Armstrong as Sunderland took the game to United and it was not long before they were rewarded for their second-half enterprise.
Stewart made space enough out wide to whip in an inch-perfect cross and beanpole striker Kyle hurled himself to send a bullet header beyond Blades keeper Paul Gerrard.
A frustrated Michael Tonge received a yellow card for his foul on Kyle, who responded by lashing a 30-yard effort over the crossbar.
Blades boss Neil Warnock sent on summer signing Jack Lester for Nick Montgomery with just under 20 minutes remaining and Tonge kept Poom on his toes from the edge of the area as the home side chased the game.
Warnock played his final hand when replacing Ashley Ward with Wayne Allison and when Arca was given his marching orders for his second bookable offence with five minutes left, Blades fans sensed another comeback.
From the resulting free-kick home defender Rob Kozluk volleyed over the crossbar, but Sunderland held firm.
In a frenetic first half Peter Ndlovu almost celebrated his 400th league appearance by getting the Blades off to a flyer, the veteran winger's shot from the edge of the area turned smartly round the post by Poom.
Ward then saw Poom deflect his shot for a corner when one-on-one with the keeper, while Arca responded for Sunderland, wriggling free to fire a left-footer from 20 yards over the crossbar.
The action was unrelenting. Poom did well to hold Tonge's cross-shot, Kozluk was booked for his challenge on Thomas Butler, Sunderland's Darren Williams also went into the book and Arca again troubled the home defence, leading full-back Kozluk a merry dance before shaving the post with another fizzing drive.
Stewart let fly from 25 yards but skewed it wide and Tonge's drilled effort was blocked by Gary Breen as both sides chased the all-important breakthrough.
Stuart McCall went close with a header, United's on-loan Fulham defender Jon Harley limped off and was replaced by Armstrong and Poom caught two goalbound efforts from Paul Peschisolido as the first half ended scoreless.