A low-key, media-only weigh-in took place on Thursday morning at the Fontainebleau hotel, before a ceremonial weigh-in later in the day at the Fillmore Miami Beach.
Heavyweights do not usually have to make weight, but Joshua was required to come in under 17st 7lb (111kg) – reflecting the gulf in experience between the fighters.
He tipped the scales at 17st 5lb (110kg), with Paul weighing 15st 7lb (98kg).
At the official weigh-in earlier, Paul stepped on the scales calmly before breaking into a brief, animated and somewhat confusing tirade.
“Do you know who I am? I am him,” he shouted, eyes wide, as he gestured towards the assembled media.
Paul was the heaviest he has weighed in at – 3lb more than for his fight against Mike Tyson last year.
The weight discrepancy has been a major talking point.
Paul has operated largely at cruiserweight for much of his boxing career.
Joshua was never expected to miss the limit, having posted a video on social media two weeks ago showing himself already on target.
He has comfortably made similar weights before, including for both fights against generational great Oleksandr Usyk. At his heaviest, he was 18st 3lb (118kg) during his professional career.