Both sides had entered the game on the back of five-match unbeaten runs and, with Middlesbrough and Hull not in league action, the visitors knew they could move into the top two.
Cardiff, however, produced their best display of Russell Slade's 16-month tenure as a Peter Whittingham double plus further goals from Anthony Pilkington and Lex Immers saw the Bluebirds find the net four times in one game for the first time since December 2012.
Dale Stephens briefly gave the Seagulls hope of a fightback but they never looked like avoiding a second away defeat of the season.
Brighton had made a solid enough start in their bid to climb the table but they fell behind against the run of play in the 16th minute.
Steven Sidwell failed to track Whittingham's forward run and the midfielder controlled Matthew Connolly's pass and gently guided the ball beyond David Stockdale and into the bottom of the net.
While the Seagulls keeper had little chance of keeping out the opener, he was culpable for the second just three minutes later.
His poor clearance fell straight to Stuart O'Keefe and Cardiff swiftly moved the ball to Pilkington through Immers. The stand-in striker cut inside his man and fired the ball through Stockdale's hands.
Brighton were stunned and Inigo Calderon's optimistic curling effort was their only real strike on goal as Cardiff buzzed with confidence.
More poor defending from the visitors made a bad situation worse as they fell 3-0 adrift on the half-hour. Connor Goldson's block tackle on Whittingham only diverted the ball across his own area and darts fanatic Immers hit the bullseye by sliding home from just inside the area.
Brighton should have pulled one back seven minutes before the break when Jiri Skalak's excellent cross found Bobby Zamora's run, but the striker could only steer wide from eight yards on his 150th league appearance for the visitors.
Chances continued to come at the other end with Tom Lawrence forcing a sharp save from Stockdale and Immers curling an effort narrowly wide either side of the interval.
Brighton's hopes of an unlikely comeback were boosted when Stephens got across his marker to glance a close-range header beyond David Marshall and it sparked their best spell of the game.
Substitute Tomer Hemed ended a smart break by driving a shot against Scott Malone, while Anthony Knockaert blazed wildly over when a poor Connolly clearance fell straight to him.
But their hopes were extinguished in the 66th minute. Pilkington tricked and teased his way into the box and drew a clumsy challenge from Goldson to leave referee Darren Bond with little option but to point to the spot.
Whittingham stepped up and emphatically despatched the spot-kick into the top corner to rubber-stamp the win.