The 27-year-old appeared to be on the brink of his first professional defeat when he was floored in the sixth round, but staged a severe onslaught to halt Klitschko in the 11th round.
Joshua successfully defended his IBF title, while also claiming the WBA ‘super’ belt, but there could be calls for a rematch after a classic heavyweight unification clash in front of a record 90,000 crowd at the national stadium.
Klitschko had overcome a heavy knockdown in the fourth and the former unified champion defied questions about his advancing age until he finally wilted to defeat after being floored twice more.
A fiery pyrotechnic show was part of Joshua’s ring walk, but he was unable to display his explosive power in a tentative first round as Klitschko kept him at bay with probing jabs.
Klitschko landed his straight right hand at the start of the second round, which was initially shrugged off by Joshua who answered with a crunching combination from close range in the third.
Seconds into the fourth round, Klitschko stunned Joshua with a booming right hand, forcing the British fighter to hold on grimly before he replied with his own powerful right.
Joshua stormed out for the fifth and floored Klitschko with a brutal barrage of punches, but the 41-year-old was far from finished and uncorked a lightning left hook to leave the home favourite in desperate trouble.
With Joshua sagging worryingly on the ropes, Klitschko appeared on the brink of a stoppage victory, as he piled on more punches.
Klitschko continued to stalk Joshua in the sixth, detonating a searing right hand to dump him heavily on the canvas, and the dazed 27-year-old staggered through the remainder of the round.
Into the seventh, Joshua started talking defiantly to his seasoned foe after eating a few more punches, but Klitschko was having the final word with his piston-like jab.
Joshua had been dragged into the longest fight of his career and tried to claw back control with two big right hands in the ninth, although he walked into a right from Klitschko in the 10th.
Sensing the need for urgency, Joshua exploded out of his corner in the 11th, and a jolting uppercut left Klitschko on unsteady legs before he was sent crashing to the canvas by further punches.
Joshua ruthlessly finished off his dazed foe, flooring him again with more savage shots, and referee David Fields signalled the finish to spark scenes of relieved celebration.
