Jamie Mackie's 58th-minute strike earned QPR a deserved share of the spoils at the Liberty Stadium.
In front of the live Sky Sports cameras, Swansea were ahead after just 14 minutes through Danny Graham.
There was a question of handball against the Swans forward in the build-up - but there was no doubting the quality of Graham's eventual shot, after he fired home a magnificent effort from 20 yards.
Rangers - who were unfortunate to be behind - continued to press and, just 12 minutes after the break, found a warranted equaliser.
Leon Britton's misplaced header after a long kick from Paddy Kenny put Mackie in the clear, before the R's attacker kept his cool to slide the Hoops level.
Both sides pushed for a second, but the draw was probably a fair outcome.
Warnock rang the changes in South Wales, making no less than three alterations to his R's side that picked up a 3-2 defeat against Sunderland in W12 on Wednesday night.
Fitz Hall, Clint Hill and Adel Taarabt were all handed starts - at the expense of Matt Connolly, Danny Gabbidon and Shaun Wright Phillips respectively.
Kenny was in goal for QPR, in a 4-2-3-1 formation.
Luke Young, Hall, Hill and Armand Traore lined up at the back.
Shaun Derry and Alejandro Faurlin were in defensive midfield, behind the more advanced trio of Joey Barton, Taarabt and Mackie.
Heidar Helguson - on target for his seventh league goal of the season against the Mackems last week - led the Rangers line in attack.
QPR made a bright start and looked tidy in possession - particularly through reintroduced Moroccan ace Taarabt.
It wasn't long before the R's carved open their first chance of the evening.
Barton's high ball from the right found Helguson at the back post, whose nod back across goal saw Mackie force a fine point-black save from Michel Vorm from all of three-yards out.
And the Swans keeper was again called into action on nine minutes - although his job was a little easier this time, comfortably collecting Helguson's tame effort low at his left-hand post.
Five minutes later, the hosts edged ahead with their first real opportunity of the contest.
Routledge's lofted cross found Graham, who eventually controlled - with suspicions of a hand ball - on the edge of the box before curling a shot low into the bottom right-hand corner of the net.
QPR were unfortunate to be behind but it could have been worse just two minutes later, after Ashley Williams headed a Britton corner just inches over the bar.
The Swans - buoyed by a now vocal home crowd - grew in confidence after their opener.
But it was still Rangers who continued to pose more questions.
Vorm was forced into an acrobatic save on 18 minutes.
Taarabt's quick free-kick into Barton saw the former Newcastle man unleash a 30-yard blast that was fantastically tipped over the bar by the Dutch shot-stopper.
Kenny pulled off a smart save from Graham's 20-yard drive eight minutes before the break, before the R's twice went close to levelling on the stroke of half time.
Young and Taarabt combined down the right, before the latter sent over a looping cross for Hill, who - stretching for the ball - sent a header over the target.
Moments later, Rangers again went close. Barton's pinpoint ball from the right found Helguson, who rose highest but saw his nodded effort clear the bar.
The R's continued to enjoy their fair share of possession after the half-time interval - going close on in the 51st minute.
Barton's ball into Taarabt on the right-hand edge of the box saw the gifted playmaker turn to fire in a low shot that was deflected just wide of the target.
QPR soon went close again. This time, free-flowing build-up play eventually ended in Faurlin cutting in from the right, before curling a shot past the far post.
Swansea themselves went within a whisker on 56 minutes.
Allen's cutting ball put Routledge through on goal who, albeit from an acute angle, dragged an effort wide of the left-hand post from close range.
Two minutes later, Rangers were deservedly on terms.
Kenny's kick up field was unintentionally headed back by Britton into the path of Mackie, who raced into the area before coolly sliding the ball past Vorm.
Minutes later and Mackie - now in the grove after his goal - again went close, driving past two players and into the box, before Vorm did well to collect the ball at his feet.
The Swans had strong appeals for a penalty turned down in the 73rd minute, following Traore's challenge on Graham in the box.
And just a minute later, the R's almost struck what would have been a contender for goal of the season.
Crisp passing play eventually ended with Faurlin exchanging passes with Taarabt.
Thereafter, the Moroccan opened his body on 25 yards before drilling a low shot towards the right-hand corner that forced a superb stop from Vorm, who turned the ball around the post.