Wickham leads the way with cool double against City.
Four-star Sunderland blew Cardiff away to move out of the bottom three with three games to play.
Almost 46,000 fans packed the Stadium of Light for a vital encounter, and the red and white army were rewarded with a clinical performance from a Sunderland side with confidence coursing through their veins.
The Black Cats didn't look back once Connor Wickham – quickly becoming a talismanic presence – headed home Seb Larsson's corner just before the half-hour.
Fabio Borini made it two on the stroke of half-time from the penalty spot after Juan Cala was dismissed for pulling back Wickham in the box.
Sunderland pulled away in the second period to seal a massively important win, with substitute Emanuele Giaccherini slotting home 14 minutes from time before Wickham headed the fourth goal - his fifth in three games - late on.
It was an emphatic display from Gus Poyet's men, who jumped three places at a vital point of the season.
Both sides went into the game fully aware of the magnitude of the encounter and the momentum was with Sunderland, with Poyet naming an unchanged side for the third successive game following a four-point return from trips to Manchester City and Chelsea.
Wickham had led the way with three goals in those two matches, and he came close just four minutes in when Cardiff keeper David Marshall turned away the striker's low shot from an extremely acute angle at the near post.
Sunderland made a bright start, although City counter-attacked well with Don Cowie volleying wide following a half-cleared corner 17 minutes in.
But that man Wickham popped up to give the Black Cats a crucial advantage with the half-hour approaching as he nodded in his sixth goal of the season for the club overall.
Larsson's corner dropped over the head of Gary Medel and Wickham cashed in, meeting the ball with an inch-perfect header into the far top corner which sneaked in between the crossbar and Peter Whittingham on the line.
The goal was just the tonic for the hosts, who took a grip on the game with Wickham, sniffing a second goal, denied by Marshall as the visiting keeper gathered his deflected shot.
Jack Colback then drove from deep to blast a powerful shot just past the base of Marshall's left-hand post as Sunderland looked to make their superiority count.
And they did so with the help of a defensive error on the stroke of half time when Wickham latched onto Cala's woeful backpass to go clear on goal, only to be clearly impeded by the Cardiff defender.
Wickham, to his credit, didn't go to ground, with referee Phil Dowd pulling play back to award the penalty after the striker had tried to squeeze home a shot.
Cala was shown a red card and Borini made no mistake from 12 yards, rolling a cool effort beyond Marshall to double the advantage.
The Italian is establishing a reputation as Sunderland's penalty king having scored several vital spot-kicks this season, and his ice-cold nerves gave the home side what proved to be an unassailable advantage.
They counter-attacked effectively against the 10 men from the get-go in the second half, with Borini curling a shot just wide before a fine cross from Johnson was inches away from finding Wickham when any touch would surely have resulted in a goal.
With the hosts finding the gaps, Borini fired wide after being teed up by Colback, but Vito Mannone still had to be alert at the other end as he produced a fine save to palm away Whittingham's awkward free-kick.
But Sunderland pushed on, playing confident football.
Poyet's men almost made it 3-0 with 18 minutes to play as Colback's low cross was turned goalwards by Borini, but Marshall somehow managed to block at point-blank range, though how much he knew about it was debatable.
And, after a confident Wickham blasted just wide, the hosts made sure of the points thanks to Giaccherini, who announced his arrival off the bench with a goal just three minutes after his introduction in place of Larsson.
It was perhaps the goal of the match, with Borini threading a lovely through ball into the path of his countryman, whose angled run beyond the defender was matched by an equally classy low finish.
Sunderland were rampant, and Colback was inches away with a rising drive which flashed beyond the angle of post and bar with Marshall well beaten.
And it was fitting that Wickham – the man around which Sunderland's revival has been built – was the man to round off the scoring with a textbook striker's goal four minutes from the end.
Giaccherini's corner dropped over the head of sub Kenwyne Jones, and the striker beat Kevin Theophile-Catherine to steer a firm header into the corner from six yards to round off a memorable – and potentially important – afternoon.
- Yellow Vergini
- Colback (Bridcutt)
- Yellow Larsson (Giaccherini)
- Yellow Borini
- Johnson (Gardner)
- Torres Ruiz Red
- da Silva (Jones) Yellow
- Medel Yellow
- Cowie (Zaha)
- Mutch Yellow
- Campbell (Bellamy)
- Yellow Gardner
- Yellow Giaccherini
- Wolff Eikrem