Joshua, 30, now joins a small cluster of men including Muhammad Ali, Lennox Lewis, Evander Holyfield, Mike Tyson and Floyd Patterson to have reclaimed the world heavyweight title.
Patterson fell to the canvas seven times in one round as he lost his belts to Ingemar Johansson in 1959 but regained them in a rematch.
The question in Saudi Arabia was whether Joshua could show the same mental fortitude after being knocked down multiple times by Ruiz in June. His answer was emphatic.
A downpour in a country that barely sees rain stopped moments before Joshua strode to the ring, prompting him to carefully dry his feet on the canvas.
From that moment on, his feet moved with grace. Seconds before the off, Ruiz was told “let’s go Andy” by his corner but he was rarely allowed to get close to his rival and inflict the damage he did in the first fight.
Anthony Joshua
Ruiz, the bookmakers’ underdog again, was cut above his left eye in the first. He landed two jabs of his own in the second but took a left hook as Joshua moved with the lightness of a man at his lowest weight in five years.
He was burning energy but was slick and showed variety in working head and body in the third. A crowd unfamiliar with the sweet science at such close quarters offered audible applause and cheers as the smart work landed.
There was always tension given the speed with which Ruiz’s gold gloves can move, and in the eighth he served up a first scare.
As the pair tangled, Ruiz made things ugly and winged in a hook.
The crowd stamped their feet while Ruiz’s fighting compatriot Saul ‘Canelo’ Alvarez stood and screamed ringside.
The ninth felt key, Joshua needed to establish distance again. He landed a solid uppercut but saw Ruiz fire back wildly instantly.
Again, the incredible durability of the champion and the constant threat he carried was evident.
Deep in the 12th, Ruiz beat his chest as if to dare Joshua close. After a night of lateral movement and poise, it was never going to happen.
Joshua glared out at the crowd as the bell sounded.
It was a look of a defiance. It was the look of a man who had proved his point.
Some seeing Ruiz’s showing here will ask what was wrong with Joshua in their first meeting – the Mexican was never able to rediscover the heights he hit in New York.
His weight gain of 15lbs was the same as James ‘Buster’ Douglas piled on after stunning Mike Tyson in 1990.
Douglas lost easily to Holyfield months later and as the scorecards widened on Saturday and Ruiz ate shots, it looked as if his new status and its attached distractions might have taken a similar toll.
Hauling 20st 3lbs around a ring is no easy feat. Only Nikolai Valuev – who was 7ft tall – has weighed more and held a world title.
And as Saudi royalty watched on at ringside, Ruiz was consistently unpicked and outmanoeuvred.
He will, at least, leave with a career-high pay day in excess of £10m.
He can live the rest of his life as a former world champion who stunned boxing.
But if he shoots for titles again, he will simply need to be better.
Joshua’s clinical response to adversity
Joshua had said defeat would have been “catastrophic” for a career that promised so much, delivered plenty and then, from nowhere, was shaken to its core.
Some close to him had expressed how nervous they were all week.
The fact his entire team stayed with him in the ring for over 30 minutes after his win pointed to their relief.
He has promised to fully explain what happened on that June night but it is to his credit that he pushed for a new approach to his training, made adjustments and lived out the lessons he gleaned from his lowest point in the paid ranks.
To use a boxing term, he ‘boxed the ears’ off a man who had prompted him to ask so many questions of himself.
The talk of facing Deontay Wilder or Tyson Fury – temporarily derailed by Ruiz in June – will resume. Another rematch, though neither party is obligated this time, also has legs.
Joshua has earned such options after such a clinical response to adversity.
Boxing history will never forget what Ruiz did to him. Joshua can at least draw some comfort in putting things right.
