Cardiff substitute Bo-Kyung Kim headed in an injury-time equaliser as Cardiff pegged the champions back for the second time in the match.
United looked set to win, but Kim struck to earn a share of the points - despite Rooney subsequently making a shocking mess of a gilt-edged chance by choosing to pass instead of shoot when in on goal in the dying seconds.
The draw saw United miss a chance to leapfrog Manchester City and claim fourth place, with City having thrashed Tottenham 6-0 earlier in the day.
Rooney's petulant kick on Jordon Mutch should almost certainly have seen him dismissed after just eight minutes of the match, but referee Neil Swarbrick decided to give him only a yellow. And the England striker made the most of his reprieve, scoring the opening goal with a superb turn-and-shoot move after Antonio Valencia's cross.
Cardiff had been kept out of the match up to that point as United had dominated possession, but Rooney's goal galvanised the hosts as they fought back with some excellent football that resulted in a well-deserved equaliser as former United youth star Campbell was the scorer, taking advantage of a stunning through-ball by Mutch - and some flat-footed defending by Jonny Evans - to finish coolly past David De Gea into the far left corner.
Just before half-time United went ahead as Rooney's corner picked out Patrice Evra, who finished his run into the box with an inch-perfect glancing header that gave David Marshall in the Cardiff goal no chance.
Cardiff seemed destined to lose out after Campbell hit the bar late on, but Peter Whittingham's free-kick picked out Kim and the Korean's perfect header gave Malky Mackay's men a richly-deserved point that helps give them some breathing space ahead of the relegation zone.
PRE-MATCH - BLUES SEEING RED OR REDS FEELING BLUE?: The Bluebirds take to the field in red while the Red Devils are playing in blue. Anyone else think that just seems plain wrong?
8' SHOCKING FOUL BY ROONEY: The England striker kicks out at Mutch in a crazy off-the-ball attack that is almost completely unprovoked, with Rooney retaliating with a full-on kick at his opponent after being muscled off the ball. He is very, very lucky only to see a yellow for that.
15' UNITED TAKE THE LEAD - AND IT'S ROONEY: The Manchester United striker latches onto a fine pass in from the right by Valencia after a defensive mix-up by Cardiff in the form of an awful Ben Turner pass, and Rooney turns brilliantly before lashing home through a sea of Cardiff City legs.
33' AN EQUALISER: It's Fraizer Campbell finishing up a blistering counter-attack move - Whittingham's long pass was inch-perfect for Mutch, who delivered a ball deep and low through the middle for Campbell to finish up from 10 yards past De Gea. Superb team goal and a wonderful finish.
45' IT'S A GOAL FOR UNITED: Evra meets Rooney's cross absolutely perfectly, the left-back runs into the box to meet the ball and Evra glances a powerful header that gives Marshall absolutely no chance.
52' MIRACULOUS SAVE: Rooney pings the free kick straight onto Fellaini's head, and it's directed straight at the bottom right corner - but David Marshall somehow dives to it and turns it round the post with his outstretched arm.
54' CARDIFF HIT THE BAR: A wonderful ball puts Campbell into space on the edge of the box - and he successfully chips over De Gea, only for the ball to come back off the underside of the bar. Just couldn't have been closer
90'+1 AN EQUALISER! AMAZING SCENES IN CARDIFF: Whittingham's delivery from a free is outstanding and straight on to Kim's head - the sub's header is bang on target and De Gea can't down to it.
90'+2 INCREDIBLE MISTAKE BY ROONEY: The United striker is in on Marshall, but decides to pass to Welbeck instead of hitting it himself - and he completely miscues it, letting Cardiff off the hook.
2 - The number of Wayne Rooney's feet that were off the ground as he attacked Jordon Mutch just eight minutes into the match.
0 - The number of red cards received by Rooney for his crackpot challenge.
5 - The number of matches that Malky Mackay has guided Cardiff through since his right-hand man Ian Moody was replaced by a 23-year-old pal of Cardiff's owner's son
625 - The number of matches Ryan Giggs played in the Premier League before getting a chance to face his hoem town club. He came on as a late sub to end that record, five days before turning 40.
Wayne Rooney: better than ever this season, but clearly still in touch with his inner thug. Can England trust him not to do anything barmy before the World Cup like he did before the Euros, and end up missing the group stage again?
MAN OF THE MATCH
Fraizer Campbell (Cardiff City): Scored his 10th goal in 16 games for Cardiff, was inches away from another, and embodied the never-say-die spirit that kept Cardiff in it.
Cardiff City: Marshall 8, Taylor 7, Caulker 7, Turner 7, Theophile-Catherine 7; Medel 7, Whittingham 7, Mutch 8, Cowie 6; Odemwingie 6, Campbell 8. Subs: Kim 8, Noone 7
Manchester United: De Gea 7, Smalling 5, Ferdinand 6, Evans 5, Evra 8, Valencia 7, Fellaini 7, Cleverley 6, Januzaj 6, Rooney 8, Hernandez 5. Subs: Welbeck 7, Giggs 6
MATCH IN A TWEET
- Sports & Recreation
- Wayne Rooney
- Manchester United
- Cardiff City
- Fraizer Campbell
- Patrice Evra
- David De Gea